Const correctness fixes that also correct bug #893146.

Fixed bugs:
  - https://launchpad.net/bugs/893146

(bzr r10783)

19 files changed, 684 insertions, 580 deletions

diff --git a/src/extension/extension.cpp b/src/extension/extension.cpp
index 72db7438c..f0b266df0 100644
--- a/src/extension/extension.cpp
+++ b/src/extension/extension.cpp
@@ -44,8 +44,6 @@ namespace Extension {
 std::vector<const gchar *> Extension::search_path;
 std::ofstream Extension::error_file;
 
-Parameter * get_param (const gchar * name);
-
 /**
     \return  none
     \brief   Constructs an Extension from a Inkscape::XML::Node
@@ -381,26 +379,7 @@ Extension::deactivated (void)
     return get_state() == STATE_DEACTIVATED;
 }
 
-/**
-    \return    Parameter structure with a name of 'name'
-    \brief     This function looks through the linked list for a parameter
-               structure with the name of the passed in name
-    \param     name   The name to search for
-
-    This is an inline function that is used by all the get_param and
-    set_param functions to find a param_t in the linked list with
-    the passed in name.
-
-    This function can throw a 'param_not_exist' exception if the
-    name is not found.
-
-    The first thing that this function checks is if the list is NULL.
-    It could be NULL because there are no parameters for this extension
-    or because all of them have been checked.  If the list
-    is NULL then the 'param_not_exist' exception is thrown.
-*/
-Parameter *
-Extension::get_param (const gchar * name)
+Parameter *Extension::get_param(gchar const *name)
 {
     if (name == NULL) {
         throw Extension::param_not_exist();
@@ -427,22 +406,14 @@ g_slist_next(list)) {
     throw Extension::param_not_exist();
 }
 
-/**
-    \return   A constant pointer to the string held by the parameters.
-    \brief    Gets a parameter identified by name with the string placed
-              in value.  It isn't duplicated into the value string.
-    \param    name    The name of the parameter to get
-    \param    doc    The document to look in for document specific parameters
-    \param    node   The node to look in for a specific parameter
+Parameter const *Extension::get_param(const gchar * name) const
+{
+    return const_cast<Extension *>(this)->get_param(name);
+}
 
-    Look up in the parameters list, then execute the function on that
-    found parameter.
-*/
-const gchar *
-Extension::get_param_string (const gchar * name, const SPDocument * doc, const Inkscape::XML::Node * node)
+gchar const *Extension::get_param_string(gchar const *name, SPDocument const *doc, Inkscape::XML::Node const *node) const
 {
-    Parameter * param;
-    param = get_param(name);
+    Parameter const *param = get_param(name);
     return param->get_string(doc, node);
 }
 
diff --git a/src/extension/extension.h b/src/extension/extension.h
index 273bc79e4..13cb409a8 100644
--- a/src/extension/extension.h
+++ b/src/extension/extension.h
@@ -173,7 +173,28 @@ public:
 private:
     void             make_param       (Inkscape::XML::Node * paramrepr);
     
-     Parameter *      get_param        (const gchar * name);
+    /**
+     * This function looks through the linked list for a parameter
+     * structure with the name of the passed in name.
+     *
+     * This is an inline function that is used by all the get_param and
+     * set_param functions to find a param_t in the linked list with
+     * the passed in name.
+     *
+     * This function can throw a 'param_not_exist' exception if the
+     * name is not found.
+     *
+     * The first thing that this function checks is if the list is NULL.
+     * It could be NULL because there are no parameters for this extension
+     * or because all of them have been checked.  If the list
+     * is NULL then the 'param_not_exist' exception is thrown.
+     *
+     * @param name The name to search for.
+     * @return Parameter structure with a name of 'name'.
+     */
+     Parameter *get_param(const gchar * name);
+
+     Parameter const *get_param(const gchar * name) const;
 
 public:
     bool             get_param_bool   (const gchar * name,
@@ -188,9 +209,19 @@ public:
                                        const SPDocument *   doc = NULL,
                                        const Inkscape::XML::Node * node = NULL);
 
-    const gchar *    get_param_string (const gchar * name,
-                                       const SPDocument *   doc = NULL,
-                                       const Inkscape::XML::Node * node = NULL);
+    /**
+     * Gets a parameter identified by name with the string placed in value.
+     * It isn't duplicated into the value string. Look up in the parameters list,
+     * then execute the function on that found parameter.
+     *
+     * @param name The name of the parameter to get.
+     * @param doc The document to look in for document specific parameters.
+     * @param node The node to look in for a specific parameter.
+     * @return A constant pointer to the string held by the parameters.
+     */
+    gchar const *get_param_string(gchar const *name,
+                                  SPDocument const *doc = NULL,
+                                  Inkscape::XML::Node const *node = NULL) const;
 
     guint32          get_param_color  (const gchar * name,
                                        const SPDocument *   doc = NULL,
diff --git a/src/extension/param/bool.h b/src/extension/param/bool.h
index 2894e8085..11d06e1c0 100644
--- a/src/extension/param/bool.h
+++ b/src/extension/param/bool.h
@@ -30,7 +30,7 @@ public:
     /**
      * Returns the current state/value.
      */
-    bool get(const SPDocument * doc, const Inkscape::XML::Node * node) const;
+    bool get(const SPDocument *doc, const Inkscape::XML::Node *node) const;
 
     /**
      * A function to set the state/value.
@@ -50,11 +50,14 @@ public:
      */
     Gtk::Widget *get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
 
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::list <std::string> &list) const { return Parameter::string(list); }
+
     /**
      * Appends 'true' or 'false'.
      * @todo investigate. Returning a value that can then be appended would probably work better/safer.
      */
-    void string(std::string &string) const;
+    virtual void string(std::string &string) const;
 
 private:
     /** Internal value. */
diff --git a/src/extension/param/color.cpp b/src/extension/param/color.cpp
index 1e5dee51c..6600d5f2a 100644
--- a/src/extension/param/color.cpp
+++ b/src/extension/param/color.cpp
@@ -3,6 +3,7 @@
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl>
  *   Christopher Brown <audiere@gmail.com>
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -73,16 +74,13 @@ ParamColor::ParamColor (const gchar * name, const gchar * guitext, const gchar *
         defaulthex = paramval.data();
 
     _value = atoi(defaulthex);
-
-    return;
 }
 
-void ParamColor::string (std::string &string)
+void ParamColor::string(std::string &string) const
 {
     char str[16];
     sprintf(str, "%i", _value);
     string += str;
-    return;
 }
 
 Gtk::Widget *ParamColor::get_widget( SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/, sigc::signal<void> * changeSignal )
diff --git a/src/extension/param/color.h b/src/extension/param/color.h
index e6b44fbcb..f46e26286 100644
--- a/src/extension/param/color.h
+++ b/src/extension/param/color.h
@@ -1,9 +1,10 @@
-#ifndef __INK_EXTENSION_PARAMCOLOR_H__
-#define __INK_EXTENSION_PARAMCOLOR_H__
+#ifndef SEEN_INK_EXTENSION_PARAMCOLOR_H__
+#define SEEN_INK_EXTENSION_PARAMCOLOR_H__
 /*
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -21,16 +22,36 @@ private:
     guint32 _value;
 public:
     ParamColor(const gchar * name, const gchar * guitext, const gchar * desc, const Parameter::_scope_t scope, bool gui_hidden, const gchar * gui_tip, Inkscape::Extension::Extension * ext, Inkscape::XML::Node * xml);
+
     virtual ~ParamColor(void);
-    /** \brief  Returns \c _value, with a \i const to protect it. */
-    guint32 get( const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/ ) { return _value; }
+
+    /** Returns \c _value, with a \i const to protect it. */
+    guint32 get( SPDocument const * /*doc*/, Inkscape::XML::Node const * /*node*/ ) const { return _value; }
+
     guint32 set (guint32 in, SPDocument * doc, Inkscape::XML::Node * node);
+
     Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-    void string (std::string &string);
+
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::list <std::string> &list) const { return Parameter::string(list); }
+
+    virtual void string (std::string &string) const;
+
     sigc::signal<void> * _changeSignal;
-}; /* class ParamColor */
+}; // class ParamColor
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
 
-#endif /* __INK_EXTENSION_PARAMCOLOR_H__ */
+#endif // SEEN_INK_EXTENSION_PARAMCOLOR_H__
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :
diff --git a/src/extension/param/enum.cpp b/src/extension/param/enum.cpp
index e25559eeb..755cc92ad 100644
--- a/src/extension/param/enum.cpp
+++ b/src/extension/param/enum.cpp
@@ -7,6 +7,7 @@
 /*
  * Author:
  *   Johan Engelen <johan@shouraizou.nl>
+ *   Jon A. Cruz <jon@joncruz.org>
  *
  * Copyright (C) 2006-2007 Johan Engelen
  *
@@ -118,8 +119,6 @@ ParamComboBox::ParamComboBox (const gchar * name, const gchar * guitext, const g
     if (defaultval != NULL) {
         _value = g_strdup(defaultval);
     }
-
-    return;
 }
 
 ParamComboBox::~ParamComboBox (void)
@@ -134,21 +133,22 @@ ParamComboBox::~ParamComboBox (void)
 }
 
 
-/** \brief  A function to set the \c _value
-    \param  in   The value to set
-    \param  doc  A document that should be used to set the value.
-    \param  node The node where the value may be placed
-
-    This function sets ONLY the internal value, but it also sets the value
-    in the preferences structure.  To put it in the right place, \c PREF_DIR
-    and \c pref_name() are used.
-
-    To copy the data into _value the old memory must be free'd first.
-    It is important to note that \c g_free handles \c NULL just fine.  Then
-    the passed in value is duplicated using \c g_strdup().
-*/
-const gchar *
-ParamComboBox::set (const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
+/**
+ * A function to set the \c _value.
+ *
+ * This function sets ONLY the internal value, but it also sets the value
+ * in the preferences structure.  To put it in the right place, \c PREF_DIR
+ *  and \c pref_name() are used.
+ *
+ * To copy the data into _value the old memory must be free'd first.
+ * It is important to note that \c g_free handles \c NULL just fine.  Then
+ * the passed in value is duplicated using \c g_strdup().
+ *
+ * @param  in   The value to set.
+ * @param  doc  A document that should be used to set the value.
+ * @param  node The node where the value may be placed.
+ */
+const gchar *ParamComboBox::set(const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
     if (in == NULL) {
         return NULL; /* Can't have NULL string */
@@ -181,22 +181,15 @@ ParamComboBox::changed (void) {
 
 }
 
-
-/**
-    \brief  A function to get the value of the parameter in string form
-    \return A string with the 'value' as command line argument
-*/
-void
-ParamComboBox::string (std::string &string)
+void ParamComboBox::string(std::string &string) const
 {
     string += _value;
-    return;
 }
 
 
 
 
-/** \brief  A special category of Gtk::Entry to handle string parameteres */
+/** A special category of Gtk::Entry to handle string parameteres. */
 class ParamComboBoxEntry : public Gtk::ComboBoxText {
 private:
     ParamComboBox * _pref;
@@ -204,10 +197,11 @@ private:
     Inkscape::XML::Node * _node;
     sigc::signal<void> * _changeSignal;
 public:
-    /** \brief  Build a string preference for the given parameter
-        \param  pref  Where to get the string from, and where to put it
-                      when it changes.
-    */
+    /**
+     * Build a string preference for the given parameter.
+     * @param  pref  Where to get the string from, and where to put it
+     *                 when it changes.
+     */
     ParamComboBoxEntry (ParamComboBox * pref, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
         Gtk::ComboBoxText(), _pref(pref), _doc(doc), _node(node), _changeSignal(changeSignal) {
         this->signal_changed().connect(sigc::mem_fun(this, &ParamComboBoxEntry::changed));
@@ -215,11 +209,12 @@ public:
     void changed (void);
 };
 
-/** \brief  Respond to the text box changing
-
-    This function responds to the box changing by grabbing the value
-    from the text box and putting it in the parameter.
-*/
+/**
+ * Respond to the text box changing.
+ *
+ * This function responds to the box changing by grabbing the value
+ * from the text box and putting it in the parameter.
+ */
 void
 ParamComboBoxEntry::changed (void)
 {
@@ -231,12 +226,11 @@ ParamComboBoxEntry::changed (void)
 }
 
 /**
-    \brief  Creates a combobox widget for an enumeration parameter
-*/
-Gtk::Widget *
-ParamComboBox::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
+ * Creates a combobox widget for an enumeration parameter.
+ */
+Gtk::Widget *ParamComboBox::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
-	if (_gui_hidden) {
+    if (_gui_hidden) {
         return NULL;
     }
 
@@ -270,5 +264,16 @@ ParamComboBox::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::s
 }
 
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :
diff --git a/src/extension/param/enum.h b/src/extension/param/enum.h
index ca008cda5..a598458c5 100644
--- a/src/extension/param/enum.h
+++ b/src/extension/param/enum.h
@@ -6,8 +6,9 @@
  */
 
 /*
- * Author:
+ * Authors:
  *   Johan Engelen <johan@shouraizou.nl>
+ *   Jon A. Cruz <jon@joncruz.org>
  *
  * Copyright (C) 2006-2007 Johan Engelen
  *
@@ -40,9 +41,14 @@ public:
     ParamComboBox(const gchar * name, const gchar * guitext, const gchar * desc, const Parameter::_scope_t scope, bool gui_hidden, const gchar * gui_tip, Inkscape::Extension::Extension * ext, Inkscape::XML::Node * xml);
     virtual ~ParamComboBox(void);
     Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-    void string (std::string &string);
 
-    const gchar * get (const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) { return _value; }
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::list <std::string> &list) const { return Parameter::string(list); }
+
+    virtual void string(std::string &string) const;
+
+    gchar const *get(SPDocument const * /*doc*/, Inkscape::XML::Node const * /*node*/) const { return _value; }
+
     const gchar * set (const gchar * in, SPDocument * doc, Inkscape::XML::Node * node);
 
     void changed (void);
diff --git a/src/extension/param/float.cpp b/src/extension/param/float.cpp
index ea6a70855..2b501a9a4 100644
--- a/src/extension/param/float.cpp
+++ b/src/extension/param/float.cpp
@@ -2,6 +2,7 @@
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -23,7 +24,7 @@ namespace Inkscape {
 namespace Extension {
 
 
-/** \brief  Use the superclass' allocator and set the \c _value */
+/** Use the superclass' allocator and set the \c _value. */
 ParamFloat::ParamFloat (const gchar * name,
                         const gchar * guitext,
                         const gchar * desc,
@@ -88,17 +89,18 @@ ParamFloat::ParamFloat (const gchar * name,
     return;
 }
 
-/** \brief  A function to set the \c _value
-    \param  in   The value to set to
-    \param  doc  A document that should be used to set the value.
-    \param  node The node where the value may be placed
-
-    This function sets the internal value, but it also sets the value
-    in the preferences structure.  To put it in the right place, \c PREF_DIR
-    and \c pref_name() are used.
-*/
-float
-ParamFloat::set (float in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
+/**
+ * A function to set the \c _value.
+ *
+ * This function sets the internal value, but it also sets the value
+ * in the preferences structure.  To put it in the right place, \c PREF_DIR
+ * and \c pref_name() are used.
+ *
+ * @param  in   The value to set to.
+ * @param  doc  A document that should be used to set the value.
+ * @param  node The node where the value may be placed.
+ */
+float ParamFloat::set(float in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
     _value = in;
     if (_value > _max) {
@@ -116,9 +118,7 @@ ParamFloat::set (float in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
     return _value;
 }
 
-/** \brief  Return the value as a string */
-void
-ParamFloat::string (std::string &string)
+void ParamFloat::string(std::string &string) const
 {
     char startstring[G_ASCII_DTOSTR_BUF_SIZE];
     g_ascii_dtostr(startstring, G_ASCII_DTOSTR_BUF_SIZE, _value);
@@ -126,15 +126,15 @@ ParamFloat::string (std::string &string)
     return;
 }
 
-/** \brief  A class to make an adjustment that uses Extension params */
+/** A class to make an adjustment that uses Extension params. */
 class ParamFloatAdjustment : public Gtk::Adjustment {
-    /** The parameter to adjust */
+    /** The parameter to adjust. */
     ParamFloat * _pref;
     SPDocument * _doc;
     Inkscape::XML::Node * _node;
     sigc::signal<void> * _changeSignal;
 public:
-    /** \brief  Make the adjustment using an extension and the string
+    /** Make the adjustment using an extension and the string
                 describing the parameter. */
     ParamFloatAdjustment (ParamFloat * param, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
             Gtk::Adjustment(0.0, param->min(), param->max(), 0.1, 1.0, 0), _pref(param), _doc(doc), _node(node), _changeSignal(changeSignal) {
@@ -146,14 +146,13 @@ public:
     void val_changed (void);
 }; /* class ParamFloatAdjustment */
 
-/** \brief  A function to respond to the value_changed signal from the
-            adjustment.
-
-    This function just grabs the value from the adjustment and writes
-    it to the parameter.  Very simple, but yet beautiful.
-*/
-void
-ParamFloatAdjustment::val_changed (void)
+/**
+ * A function to respond to the value_changed signal from the adjustment.
+ *
+ * This function just grabs the value from the adjustment and writes
+ * it to the parameter.  Very simple, but yet beautiful.
+ */
+void ParamFloatAdjustment::val_changed(void)
 {
     //std::cout << "Value Changed to: " << this->get_value() << std::endl;
     _pref->set(this->get_value(), _doc, _node);
@@ -164,14 +163,13 @@ ParamFloatAdjustment::val_changed (void)
 }
 
 /**
-    \brief  Creates a Float Adjustment for a float parameter
-
-    Builds a hbox with a label and a float adjustment in it.
-*/
-Gtk::Widget *
-ParamFloat::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
+ * Creates a Float Adjustment for a float parameter.
+ *
+ * Builds a hbox with a label and a float adjustment in it.
+ */
+Gtk::Widget * ParamFloat::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
-	if (_gui_hidden) {
+    if (_gui_hidden) {
         return NULL;
     }
 
diff --git a/src/extension/param/float.h b/src/extension/param/float.h
index a2c19441d..24747b5f1 100644
--- a/src/extension/param/float.h
+++ b/src/extension/param/float.h
@@ -5,6 +5,7 @@
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -30,16 +31,26 @@ public:
                 Inkscape::Extension::Extension * ext,
                 Inkscape::XML::Node * xml,
                 AppearanceMode mode);
-    /** \brief  Returns \c _value */
-    float get (const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) { return _value; }
+    /** Returns \c _value. */
+    float get(const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) const { return _value; }
+
     float set (float in, SPDocument * doc, Inkscape::XML::Node * node);
+
     float max (void) { return _max; }
+
     float min (void) { return _min; }
+
     float precision (void) { return _precision; }
+
     Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-    void string (std::string &string);
+
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::list <std::string> &list) const { return Parameter::string(list); }
+
+    virtual void string(std::string &string) const;
+
 private:
-    /** \brief  Internal value. */
+    /** Internal value. */
     float _value;
     AppearanceMode _mode;
     int _indent;
diff --git a/src/extension/param/int.cpp b/src/extension/param/int.cpp
index 090441c17..cd6815c4d 100644
--- a/src/extension/param/int.cpp
+++ b/src/extension/param/int.cpp
@@ -2,6 +2,7 @@
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -23,7 +24,7 @@ namespace Inkscape {
 namespace Extension {
 
 
-/** \brief  Use the superclass' allocator and set the \c _value */
+/** Use the superclass' allocator and set the \c _value. */
 ParamInt::ParamInt (const gchar * name,
                     const gchar * guitext,
                     const gchar * desc,
@@ -77,21 +78,19 @@ ParamInt::ParamInt (const gchar * name,
     if (_value < _min) {
         _value = _min;
     }
-
-    return;
 }
 
-/** \brief  A function to set the \c _value
-    \param  in   The value to set to
-    \param  doc  A document that should be used to set the value.
-    \param  node The node where the value may be placed
-
-    This function sets the internal value, but it also sets the value
-    in the preferences structure.  To put it in the right place, \c PREF_DIR
-    and \c pref_name() are used.
-*/
-int
-ParamInt::set (int in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
+/**
+ * A function to set the \c _value.
+ * This function sets the internal value, but it also sets the value
+ * in the preferences structure.  To put it in the right place, \c PREF_DIR
+ * and \c pref_name() are used.
+ *
+ * @param  in   The value to set to.
+ * @param  doc  A document that should be used to set the value.
+ * @param  node The node where the value may be placed.
+ */
+int ParamInt::set(int in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
     _value = in;
     if (_value > _max) {
@@ -109,48 +108,45 @@ ParamInt::set (int in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
     return _value;
 }
 
-/** \brief  A class to make an adjustment that uses Extension params */
+/** A class to make an adjustment that uses Extension params. */
 class ParamIntAdjustment : public Gtk::Adjustment {
-    /** The parameter to adjust */
+    /** The parameter to adjust. */
     ParamInt * _pref;
     SPDocument * _doc;
     Inkscape::XML::Node * _node;
     sigc::signal<void> * _changeSignal;
 public:
-    /** \brief  Make the adjustment using an extension and the string
-                describing the parameter. */
+    /** Make the adjustment using an extension and the string
+        describing the parameter. */
     ParamIntAdjustment (ParamInt * param, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
             Gtk::Adjustment(0.0, param->min(), param->max(), 1.0, 10.0, 0), _pref(param), _doc(doc), _node(node), _changeSignal(changeSignal) {
         this->set_value(_pref->get(NULL, NULL) /* \todo fix */);
         this->signal_value_changed().connect(sigc::mem_fun(this, &ParamIntAdjustment::val_changed));
-        return;
     };
 
     void val_changed (void);
 }; /* class ParamIntAdjustment */
 
-/** \brief  A function to respond to the value_changed signal from the
-            adjustment.
-
-    This function just grabs the value from the adjustment and writes
-    it to the parameter.  Very simple, but yet beautiful.
-*/
-void
-ParamIntAdjustment::val_changed (void)
+/**
+ * A function to respond to the value_changed signal from the adjustment.
+ *
+ * This function just grabs the value from the adjustment and writes
+ * it to the parameter.  Very simple, but yet beautiful.
+ */
+void ParamIntAdjustment::val_changed(void)
 {
     //std::cout << "Value Changed to: " << this->get_value() << std::endl;
     _pref->set((int)this->get_value(), _doc, _node);
     if (_changeSignal != NULL) {
         _changeSignal->emit();
     }
-    return;
 }
 
 /**
-    \brief  Creates a Int Adjustment for a int parameter
-
-    Builds a hbox with a label and a int adjustment in it.
-*/
+ * Creates a Int Adjustment for a int parameter.
+ *
+ * Builds a hbox with a label and a int adjustment in it.
+ */
 Gtk::Widget *
 ParamInt::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
@@ -183,18 +179,15 @@ ParamInt::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal
     return dynamic_cast<Gtk::Widget *>(hbox);
 }
 
-/** \brief  Return the value as a string */
-void
-ParamInt::string (std::string &string)
+void ParamInt::string(std::string &string) const
 {
     char startstring[32];
     sprintf(startstring, "%d", _value);
     string += startstring;
-    return;
 }
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
 
 /*
   Local Variables:
diff --git a/src/extension/param/int.h b/src/extension/param/int.h
index 138368ff3..83fc67be9 100644
--- a/src/extension/param/int.h
+++ b/src/extension/param/int.h
@@ -5,6 +5,7 @@
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -30,15 +31,25 @@ public:
               Inkscape::Extension::Extension * ext,
               Inkscape::XML::Node * xml,
               AppearanceMode mode);
-    /** \brief  Returns \c _value */
-    int get (const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) { return _value; }
+
+    /** Returns \c _value. */
+    int get(const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) const { return _value; }
+
     int set (int in, SPDocument * doc, Inkscape::XML::Node * node);
+
     int max (void) { return _max; }
+
     int min (void) { return _min; }
+
     Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-    void string (std::string &string);
+
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::list <std::string> &list) const { return Parameter::string(list); }
+
+    virtual void string(std::string &string) const;
+
 private:
-    /** \brief  Internal value. */
+    /** Internal value. */
     int _value;
     AppearanceMode _mode;
     int _indent;
diff --git a/src/extension/param/notebook.cpp b/src/extension/param/notebook.cpp
index 637208b04..80042febc 100644
--- a/src/extension/param/notebook.cpp
+++ b/src/extension/param/notebook.cpp
@@ -3,8 +3,9 @@
  */
 
 /*
- * Author:
+ * Authors:
  *   Johan Engelen <johan@shouraizou.nl>
+ *   Jon A. Cruz <jon@joncruz.org>
  *
  * Copyright (C) 2006 Author
  *
@@ -33,15 +34,19 @@
 
 #include "notebook.h"
 
-/** \brief  The root directory in the preferences database for extension
-            related parameters. */
+/**
+ * The root directory in the preferences database for extension
+ * related parameters.
+ */
 #define PREF_DIR "extensions"
 
 namespace Inkscape {
 namespace Extension {
 
 
-// \brief  A class to represent the pages of a notebookparameter of an extension
+/**
+ * A class to represent the pages of a notebookparameter of an extension.
+ */
 class ParamNotebookPage : public Parameter {
 private:
     GSList * parameters; /**< A table to store the parameters for this page.
@@ -85,8 +90,6 @@ ParamNotebookPage::ParamNotebookPage (const gchar * name, const gchar * guitext,
             child_repr = sp_repr_next(child_repr);
         }
     }
-
-    return;
 }
 
 ParamNotebookPage::~ParamNotebookPage (void)
@@ -100,16 +103,13 @@ ParamNotebookPage::~ParamNotebookPage (void)
     g_slist_free(parameters);
 }
 
-/** \brief  Return the value as a string */
-void
-ParamNotebookPage::paramString (std::list <std::string> &list)
+/** Return the value as a string. */
+void ParamNotebookPage::paramString(std::list <std::string> &list)
 {
     for (GSList * plist = parameters; plist != NULL; plist = g_slist_next(plist)) {
         Parameter * param = reinterpret_cast<Parameter *>(plist->data);
         param->string(list);
     }
-
-    return;
 }
 
 
@@ -193,16 +193,19 @@ ParamNotebookPage::makepage (Inkscape::XML::Node * in_repr, Inkscape::Extension:
 
 
 /**
-    \brief  Creates a notebookpage widget for a notebook
-
-    Builds a notebook page (a vbox) and puts parameters on it.
-*/
-Gtk::Widget *
-ParamNotebookPage::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
+ * Creates a notebookpage widget for a notebook.
+ *
+ * Builds a notebook page (a vbox) and puts parameters on it.
+ */
+Gtk::Widget * ParamNotebookPage::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
-	if (_gui_hidden) return NULL;
+    if (_gui_hidden) {
+        return NULL;
+    }
 
-    if (!_tooltips) _tooltips = new Gtk::Tooltips();
+    if (!_tooltips) {
+        _tooltips = new Gtk::Tooltips();
+    }
 
     Gtk::VBox * vbox = Gtk::manage(new Gtk::VBox);
     vbox->set_border_width(5);
@@ -266,8 +269,6 @@ ParamNotebook::ParamNotebook (const gchar * name, const gchar * guitext, const g
         defaultval = paramval.data();
     if (defaultval != NULL)
         _value = g_strdup(defaultval);  // allocate space for _value
-
-    return;
 }
 
 ParamNotebook::~ParamNotebook (void)
@@ -283,21 +284,22 @@ ParamNotebook::~ParamNotebook (void)
 }
 
 
-/** \brief  A function to set the \c _value
-    \param  in   The number of the page which value must be set
-    \param  doc  A document that should be used to set the value.
-    \param  node The node where the value may be placed
-
-    This function sets the internal value, but it also sets the value
-    in the preferences structure.  To put it in the right place, \c PREF_DIR
-    and \c pref_name() are used.
-
-    To copy the data into _value the old memory must be free'd first.
-    It is important to note that \c g_free handles \c NULL just fine.  Then
-    the passed in value is duplicated using \c g_strdup().
-*/
-const gchar *
-ParamNotebook::set (const int in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
+/**
+ * A function to set the \c _value.
+ *
+ * This function sets the internal value, but it also sets the value
+ * in the preferences structure.  To put it in the right place, \c PREF_DIR
+ * and \c pref_name() are used.
+ *
+ * To copy the data into _value the old memory must be free'd first.
+ * It is important to note that \c g_free handles \c NULL just fine.  Then
+ * the passed in value is duplicated using \c g_strdup().
+ *
+ * @param  in   The number of the page which value must be set.
+ * @param  doc  A document that should be used to set the value.
+ * @param  node The node where the value may be placed.
+ */
+const gchar *ParamNotebook::set(const int in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
     ParamNotebookPage * page = NULL;
     int i = 0;
@@ -319,13 +321,7 @@ ParamNotebook::set (const int in, SPDocument * /*doc*/, Inkscape::XML::Node * /*
     return _value;
 }
 
-
-/**
-    \brief  A function to get the currentpage and the parameters in a string form
-    \return A string with the 'value' and all the parameters on all pages as command line arguments
-*/
-void
-ParamNotebook::string (std::list <std::string> &list)
+void ParamNotebook::string(std::list <std::string> &list) const
 {
     std::string param_string;
     param_string += "--";
@@ -341,51 +337,47 @@ ParamNotebook::string (std::list <std::string> &list)
         ParamNotebookPage * page = reinterpret_cast<ParamNotebookPage *>(pglist->data);
         page->paramString(list);
     }
-
-    return;
 }
 
-/** \brief  A special category of Gtk::Notebook to handle notebook parameters */
+/** A special category of Gtk::Notebook to handle notebook parameters. */
 class ParamNotebookWdg : public Gtk::Notebook {
 private:
     ParamNotebook * _pref;
     SPDocument * _doc;
     Inkscape::XML::Node * _node;
 public:
-    /** \brief  Build a notebookpage preference for the given parameter
-        \param  pref  Where to get the string (pagename) from, and where to put it
-                      when it changes.
-    */
+    /**
+     * Build a notebookpage preference for the given parameter.
+     * @param  pref  Where to get the string (pagename) from, and where to put it
+     *               when it changes.
+     */
     ParamNotebookWdg (ParamNotebook * pref, SPDocument * doc, Inkscape::XML::Node * node) :
         Gtk::Notebook(), _pref(pref), _doc(doc), _node(node), activated(false) {
         // don't have to set the correct page: this is done in ParamNotebook::get_widget.
         // hook function
         this->signal_switch_page().connect(sigc::mem_fun(this, &ParamNotebookWdg::changed_page));
-        return;
     };
     void changed_page(GtkNotebookPage *page, guint pagenum);
     bool activated;
 };
 
-/** \brief  Respond to the selected page of notebook changing
-    This function responds to the changing by reporting it to
-    ParamNotebook. The change is only reported when the notebook
-    is actually visible. This to exclude 'fake' changes when the
-    notebookpages are added or removed.
-*/
-void
-ParamNotebookWdg::changed_page(GtkNotebookPage */*page*/,
-                                   guint pagenum)
+/**
+ * Respond to the selected page of notebook changing.
+ * This function responds to the changing by reporting it to
+ * ParamNotebook. The change is only reported when the notebook
+ * is actually visible. This to exclude 'fake' changes when the
+ * notebookpages are added or removed.
+ */
+void ParamNotebookWdg::changed_page(GtkNotebookPage */*page*/,
+                                    guint pagenum)
 {
     if (is_visible()) {
         _pref->set((int)pagenum, _doc, _node);
     }
-    return;
 }
 
-/** \brief  Search the parameter's name in the notebook content */
-Parameter *
-ParamNotebook::get_param(const gchar * name)
+/** Search the parameter's name in the notebook content. */
+Parameter *ParamNotebook::get_param(const gchar * name)
 {
     if (name == NULL) {
         throw Extension::param_not_exist();
@@ -401,9 +393,8 @@ ParamNotebook::get_param(const gchar * name)
     return NULL;
 }
 
-/** \brief  Search the parameter's name in the page content */
-Parameter *
-ParamNotebookPage::get_param(const gchar * name)
+/** Search the parameter's name in the page content. */
+Parameter *ParamNotebookPage::get_param(const gchar * name)
 {
     if (name == NULL) {
         throw Extension::param_not_exist();
@@ -424,14 +415,15 @@ ParamNotebookPage::get_param(const gchar * name)
 }
 
 /**
-    \brief  Creates a Notebook widget for a notebook parameter
-
-    Builds a notebook and puts pages in it.
-*/
-Gtk::Widget *
-ParamNotebook::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
+ * Creates a Notebook widget for a notebook parameter.
+ *
+ * Builds a notebook and puts pages in it.
+ */
+Gtk::Widget * ParamNotebook::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
-	if (_gui_hidden) return NULL;
+    if (_gui_hidden) {
+        return NULL;
+    }
 
     ParamNotebookWdg * nb = Gtk::manage(new ParamNotebookWdg(this, doc, node));
 
@@ -456,8 +448,8 @@ ParamNotebook::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::s
 }
 
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
 
 /*
   Local Variables:
diff --git a/src/extension/param/notebook.h b/src/extension/param/notebook.h
index 983ad3161..23058f465 100644
--- a/src/extension/param/notebook.h
+++ b/src/extension/param/notebook.h
@@ -8,6 +8,7 @@
 /*
  * Author:
  *   Johan Engelen <johan@shouraizou.nl>
+ *   Jon A. Cruz <jon@joncruz.org>
  *
  * Copyright (C) 2006 Author
  *
@@ -26,12 +27,14 @@ namespace Extension {
 class Extension;
 
 
-// \brief  A class to represent a notebookparameter of an extension
+/** A class to represent a notebookparameter of an extension. */
 class ParamNotebook : public Parameter {
 private:
-    /** \brief  Internal value.  This should point to a string that has
-                been allocated in memory.  And should be free'd.
-                It is the name of the current page. */
+    /**
+     * Internal value.  This should point to a string that has
+     * been allocated in memory.  And should be free'd.
+     * It is the name of the current page.
+     */
     gchar * _value;
 
     GSList * pages; /**< A table to store the pages with parameters for this notebook.
@@ -41,7 +44,16 @@ public:
     ParamNotebook(const gchar * name, const gchar * guitext, const gchar * desc, const Parameter::_scope_t scope, bool gui_hidden, const gchar * gui_tip, Inkscape::Extension::Extension * ext, Inkscape::XML::Node * xml);
     virtual ~ParamNotebook(void);
     Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-    void string (std::list <std::string> &list);
+
+    /**
+     * A function to get the currentpage and the parameters in a string form.
+     * @return A string with the 'value' and all the parameters on all pages as command line arguments.
+     */
+    virtual void string (std::list <std::string> &list) const;
+
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::string &string) const {return Parameter::string(string);}
+
 
     Parameter * get_param (const gchar * name);
 
@@ -53,8 +65,8 @@ public:
 
 
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
 
 #endif /* INK_EXTENSION_PARAMNOTEBOOK_H_SEEN */
 
diff --git a/src/extension/param/parameter.cpp b/src/extension/param/parameter.cpp
index 106cd76a6..063ec32be 100644
--- a/src/extension/param/parameter.cpp
+++ b/src/extension/param/parameter.cpp
@@ -1,5 +1,5 @@
 /** @file
- * @brief Parameters for extensions.
+ * Parameters for extensions.
  */
 /* Author:
  *   Ted Gould <ted@gould.cx>
@@ -42,76 +42,52 @@
 namespace Inkscape {
 namespace Extension {
 
-/**
-    \return None
-    \brief  This function creates a parameter that can be used later.  This
-            is typically done in the creation of the extension and defined
-            in the XML file describing the extension (it's private so people
-            have to use the system) :)
-    \param  in_repr  The XML describing the parameter
-
-    This function first grabs all of the data out of the Repr and puts
-    it into local variables.  Actually, these are just pointers, and the
-    data is not duplicated so we need to be careful with it.  If there
-    isn't a name or a type in the XML, then no parameter is created as
-    the function just returns.
-
-    From this point on, we're pretty committed as we've allocated an
-    object and we're starting to fill it.  The name is set first, and
-    is created with a strdup to actually allocate memory for it.  Then
-    there is a case statement (roughly because strcmp requires 'ifs')
-    based on what type of parameter this is.  Depending which type it
-    is, the value is interpreted differently, but they are relatively
-    straight forward.  In all cases the value is set to the default
-    value from the XML and the type is set to the interpreted type.
-*/
-Parameter *
-Parameter::make (Inkscape::XML::Node * in_repr, Inkscape::Extension::Extension * in_ext)
+Parameter *Parameter::make(Inkscape::XML::Node *in_repr, Inkscape::Extension::Extension *in_ext)
 {
-    const char * name;
-    const char * type;
-    const char * guitext;
-    const char * desc;
-    const char * scope_str;
-    Parameter::_scope_t scope = Parameter::SCOPE_USER;
-	bool gui_hidden = false;
-	const char * gui_hide;
-	const char * gui_tip;
-
-    name = in_repr->attribute("name");
-    type = in_repr->attribute("type");
-    guitext = in_repr->attribute("gui-text");
-    if (guitext == NULL)
+    const char *name = in_repr->attribute("name");
+    const char *type = in_repr->attribute("type");
+
+    // In this case we just don't have enough information
+    if (!name || !type) {
+        return NULL;
+    }
+
+    const char *guitext = in_repr->attribute("gui-text");
+    if (guitext == NULL) {
         guitext = in_repr->attribute("_gui-text");
-    gui_tip = in_repr->attribute("gui-tip");
-    if (gui_tip == NULL)
+    }
+    const char *gui_tip = in_repr->attribute("gui-tip");
+    if (gui_tip == NULL) {
         gui_tip = in_repr->attribute("_gui-tip");
-    desc = in_repr->attribute("gui-description");
-    if (desc == NULL)
+    }
+    const char *desc = in_repr->attribute("gui-description");
+    if (desc == NULL) {
         desc = in_repr->attribute("_gui-description");
-    scope_str = in_repr->attribute("scope");
-	gui_hide = in_repr->attribute("gui-hidden");
-	if (gui_hide != NULL) {
-		if (strcmp(gui_hide, "1") == 0 ||
-			strcmp(gui_hide, "true") == 0) {
-			gui_hidden = true;
-		}
-		/* else stays false */
-	}
-    const gchar* appearance = in_repr->attribute("appearance");
-
-    /* In this case we just don't have enough information */
-    if (name == NULL || type == NULL) {
-        return NULL;
     }
+    bool gui_hidden = false;
+    {
+        const char *gui_hide = in_repr->attribute("gui-hidden");
+        if (gui_hide != NULL) {
+            if (strcmp(gui_hide, "1") == 0 ||
+                strcmp(gui_hide, "true") == 0) {
+                gui_hidden = true;
+            }
+            /* else stays false */
+        }
+    }
+    const gchar* appearance = in_repr->attribute("appearance");
 
-    if (scope_str != NULL) {
-        if (!strcmp(scope_str, "user")) {
-            scope = Parameter::SCOPE_USER;
-        } else if (!strcmp(scope_str, "document")) {
-            scope = Parameter::SCOPE_DOCUMENT;
-        } else if (!strcmp(scope_str, "node")) {
-            scope = Parameter::SCOPE_NODE;
+    Parameter::_scope_t scope = Parameter::SCOPE_USER;
+    {
+        const char *scope_str = in_repr->attribute("scope");
+        if (scope_str != NULL) {
+            if (!strcmp(scope_str, "user")) {
+                scope = Parameter::SCOPE_USER;
+            } else if (!strcmp(scope_str, "document")) {
+                scope = Parameter::SCOPE_DOCUMENT;
+            } else if (!strcmp(scope_str, "node")) {
+                scope = Parameter::SCOPE_NODE;
+            }
         }
     }
 
@@ -132,10 +108,10 @@ Parameter::make (Inkscape::XML::Node * in_repr, Inkscape::Extension::Extension *
         }
     } else if (!strcmp(type, "string")) {
         param = new ParamString(name, guitext, desc, scope, gui_hidden, gui_tip, in_ext, in_repr);
-        const gchar * max_length = in_repr->attribute("max_length");
+        gchar const * max_length = in_repr->attribute("max_length");
         if (max_length != NULL) {
-        	ParamString * ps = dynamic_cast<ParamString *>(param);
-        	ps->setMaxLength(atoi(max_length));
+            ParamString * ps = dynamic_cast<ParamString *>(param);
+            ps->setMaxLength(atoi(max_length));
         }
     } else if (!strcmp(type, "description")) {
         if (appearance && !strcmp(appearance, "header")) {
@@ -157,82 +133,74 @@ Parameter::make (Inkscape::XML::Node * in_repr, Inkscape::Extension::Extension *
         param = new ParamColor(name, guitext, desc, scope, gui_hidden, gui_tip, in_ext, in_repr);
     }
 
-    /* Note: param could equal NULL */
+    // Note: param could equal NULL
     return param;
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-bool
-Parameter::get_bool (const SPDocument * doc, const Inkscape::XML::Node * node)
+bool Parameter::get_bool(SPDocument const *doc, Inkscape::XML::Node const *node) const
 {
-    ParamBool * boolpntr = dynamic_cast<ParamBool *>(this);
-    if (boolpntr == NULL)
+    ParamBool const *boolpntr = dynamic_cast<ParamBool const *>(this);
+    if (!boolpntr) {
         throw Extension::param_not_bool_param();
+    }
     return boolpntr->get(doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-int
-Parameter::get_int (const SPDocument * doc, const Inkscape::XML::Node * node)
+int Parameter::get_int(SPDocument const *doc, Inkscape::XML::Node const *node) const
 {
-    ParamInt * intpntr = dynamic_cast<ParamInt *>(this);
-    if (intpntr == NULL)
+    ParamInt const *intpntr = dynamic_cast<ParamInt const *>(this);
+    if (!intpntr) {
         throw Extension::param_not_int_param();
+    }
     return intpntr->get(doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-float
-Parameter::get_float (const SPDocument * doc, const Inkscape::XML::Node * node)
+float Parameter::get_float(SPDocument const *doc, Inkscape::XML::Node const *node) const
 {
-    ParamFloat * floatpntr = dynamic_cast<ParamFloat *>(this);
-    if (floatpntr == NULL)
+    ParamFloat const *floatpntr = dynamic_cast<ParamFloat const *>(this);
+    if (!floatpntr) {
         throw Extension::param_not_float_param();
+    }
     return floatpntr->get(doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-const gchar *
-Parameter::get_string (const SPDocument * doc, const Inkscape::XML::Node * node)
+gchar const *Parameter::get_string(SPDocument const *doc, Inkscape::XML::Node const *node) const
 {
-    ParamString * stringpntr = dynamic_cast<ParamString *>(this);
-    if (stringpntr == NULL)
+    ParamString const *stringpntr = dynamic_cast<ParamString const *>(this);
+    if (!stringpntr) {
         throw Extension::param_not_string_param();
+    }
     return stringpntr->get(doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-const gchar *
-Parameter::get_enum (const SPDocument * doc, const Inkscape::XML::Node * node)
+gchar const *Parameter::get_enum(SPDocument const *doc, Inkscape::XML::Node const *node) const
 {
-    ParamComboBox * param = dynamic_cast<ParamComboBox *>(this);
-    if (param == NULL)
+    ParamComboBox const *param = dynamic_cast<ParamComboBox const *>(this);
+    if (!param) {
         throw Extension::param_not_enum_param();
+    }
     return param->get(doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-gchar const *Parameter::get_optiongroup(SPDocument const * doc, Inkscape::XML::Node const * node)
+gchar const *Parameter::get_optiongroup(SPDocument const *doc, Inkscape::XML::Node const * node) const
 {
-    ParamRadioButton * param = dynamic_cast<ParamRadioButton *>(this);
+    ParamRadioButton const *param = dynamic_cast<ParamRadioButton const *>(this);
     if (!param) {
         throw Extension::param_not_optiongroup_param();
     }
     return param->get(doc, node);
 }
 
-guint32
-Parameter::get_color(const SPDocument* doc, const Inkscape::XML::Node* node)
+guint32 Parameter::get_color(const SPDocument* doc, Inkscape::XML::Node const *node) const
 {
-    ParamColor* param = dynamic_cast<ParamColor *>(this);
-    if (param == NULL)
+    ParamColor const *param = dynamic_cast<ParamColor const *>(this);
+    if (!param) {
         throw Extension::param_not_color_param();
+    }
     return param->get(doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-bool
-Parameter::set_bool (bool in, SPDocument * doc, Inkscape::XML::Node * node)
+bool Parameter::set_bool(bool in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamBool * boolpntr = dynamic_cast<ParamBool *>(this);
     if (boolpntr == NULL)
@@ -240,9 +208,7 @@ Parameter::set_bool (bool in, SPDocument * doc, Inkscape::XML::Node * node)
     return boolpntr->set(in, doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-int
-Parameter::set_int (int in, SPDocument * doc, Inkscape::XML::Node * node)
+int Parameter::set_int(int in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamInt * intpntr = dynamic_cast<ParamInt *>(this);
     if (intpntr == NULL)
@@ -250,7 +216,7 @@ Parameter::set_int (int in, SPDocument * doc, Inkscape::XML::Node * node)
     return intpntr->set(in, doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
+/** Wrapper to cast to the object and use it's function. */
 float
 Parameter::set_float (float in, SPDocument * doc, Inkscape::XML::Node * node)
 {
@@ -261,9 +227,9 @@ Parameter::set_float (float in, SPDocument * doc, Inkscape::XML::Node * node)
     return floatpntr->set(in, doc, node);
 }
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
-const gchar *
-Parameter::set_string (const gchar * in, SPDocument * doc, Inkscape::XML::Node * node)
+/** Wrapper to cast to the object and use it's function. */
+gchar const *
+Parameter::set_string (gchar const * in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamString * stringpntr = dynamic_cast<ParamString *>(this);
     if (stringpntr == NULL)
@@ -281,7 +247,7 @@ gchar const * Parameter::set_optiongroup( gchar const * in, SPDocument * doc, In
 }
 
 
-/** \brief  Wrapper to cast to the object and use it's function.  */
+/** Wrapper to cast to the object and use it's function. */
 guint32
 Parameter::set_color (guint32 in, SPDocument * doc, Inkscape::XML::Node * node)
 {
@@ -292,9 +258,15 @@ Parameter::set_color (guint32 in, SPDocument * doc, Inkscape::XML::Node * node)
 }
 
 
-/** \brief  Oop, now that we need a parameter, we need it's name.  */
-Parameter::Parameter (const gchar * name, const gchar * guitext, const gchar * desc, const Parameter::_scope_t scope, bool gui_hidden, const gchar * gui_tip, Inkscape::Extension::Extension * ext) :
-    extension(ext), _name(NULL), _desc(NULL), _scope(scope), _text(NULL), _gui_hidden(gui_hidden), _gui_tip(NULL)
+/** Oop, now that we need a parameter, we need it's name. */
+Parameter::Parameter(gchar const * name, gchar const * guitext, gchar const * desc, const Parameter::_scope_t scope, bool gui_hidden, gchar const * gui_tip, Inkscape::Extension::Extension * ext) :
+    _desc(0),
+    _scope(scope),
+    _text(0),
+    _gui_hidden(gui_hidden),
+    _gui_tip(0),
+    extension(ext),
+    _name(0)
 {
     if (name != NULL) {
         _name = g_strdup(name);
@@ -316,9 +288,15 @@ Parameter::Parameter (const gchar * name, const gchar * guitext, const gchar * d
     return;
 }
 
-/** \brief  Oop, now that we need a parameter, we need it's name.  */
-Parameter::Parameter (const gchar * name, const gchar * guitext, Inkscape::Extension::Extension * ext) :
-    extension(ext), _name(NULL), _desc(NULL), _scope(Parameter::SCOPE_USER), _text(NULL), _gui_hidden(false), _gui_tip(NULL)
+/** Oop, now that we need a parameter, we need it's name. */
+Parameter::Parameter (gchar const * name, gchar const * guitext, Inkscape::Extension::Extension * ext) :
+    _desc(0),
+    _scope(Parameter::SCOPE_USER),
+    _text(0),
+    _gui_hidden(false),
+    _gui_tip(0),
+    extension(ext),
+    _name(0)
 {
     if (name != NULL) {
         _name = g_strdup(name);
@@ -332,19 +310,22 @@ Parameter::Parameter (const gchar * name, const gchar * guitext, Inkscape::Exten
     return;
 }
 
-/** \brief  Just free the allocated name. */
-Parameter::~Parameter (void)
+Parameter::~Parameter(void)
 {
     g_free(_name);
+    _name = 0;
+
     g_free(_text);
-	g_free(_gui_tip);
+    _text = 0;
+
+    g_free(_gui_tip);
+    _gui_tip = 0;
+
     g_free(_desc);
+    _desc = 0;
 }
 
-/** \brief  Build the name to write the parameter from the extension's
-            ID and the name of this parameter. */
-gchar *
-Parameter::pref_name (void)
+gchar *Parameter::pref_name(void) const
 {
     return g_strdup_printf("%s.%s", extension->get_id(), _name);
 }
@@ -395,49 +376,43 @@ Inkscape::XML::Node *Parameter::document_param_node(SPDocument * doc)
     return params;
 }
 
-/** \brief  Basically, if there is no widget pass a NULL. */
+/** Basically, if there is no widget pass a NULL. */
 Gtk::Widget *
 Parameter::get_widget (SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/, sigc::signal<void> * /*changeSignal*/)
 {
     return NULL;
 }
 
-/** \brief  If I'm not sure which it is, just don't return a value. */
-void
-Parameter::string (std::string &/*string*/)
+/** If I'm not sure which it is, just don't return a value. */
+void Parameter::string(std::string &/*string*/) const
 {
-    return;
+    // TODO investigate clearing the target string.
 }
 
-void
-Parameter::string (std::list <std::string> &list)
+void Parameter::string(std::list <std::string> &list) const
 {
     std::string value;
     string(value);
-    if (value == "") {
-        return;
+    if (!value.empty()) {
+        std::string final;
+        final += "--";
+        final += name();
+        final += "=";
+        final += value;
+
+        list.insert(list.end(), final);
     }
-
-    std::string final;
-    final += "--";
-    final += name();
-    final += "=";
-    final += value;
-
-    list.insert(list.end(), final);
-    return;
 }
 
-/** All the code in Notebook::get_param to get the notebook content. */
-Parameter *Parameter::get_param(const gchar * /*name*/)
+Parameter *Parameter::get_param(gchar const * /*name*/)
 {
     return NULL;
 }
 
 Glib::ustring const extension_pref_root = "/extensions/";
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
 
 /*
   Local Variables:
diff --git a/src/extension/param/parameter.h b/src/extension/param/parameter.h
index ad07f5306..8d80e6c40 100644
--- a/src/extension/param/parameter.h
+++ b/src/extension/param/parameter.h
@@ -1,8 +1,9 @@
 /** @file
- * @brief Parameters for extensions.
+ * Parameters for extensions.
  */
 /* Authors:
  *   Ted Gould <ted@gould.cx>
+ *   Jon A. Cruz <jon@joncruz.org>
  *
  * Copyright (C) 2005-2006 Authors
  *
@@ -27,108 +28,169 @@ class Extension;
 
 
 /**
- * @brief The root directory in the preferences database for extension-related parameters
+ * The root directory in the preferences database for extension-related parameters.
  *
  * The directory path has both a leading and a trailing slash, so that extension_pref_root + pref_name works
  * without having to append a separator.
  */
 extern Glib::ustring const extension_pref_root;
 
-/** \brief  A class to represent the parameter of an extension
-
-    This is really a super class that allows them to abstract all
-    the different types of parameters into some that can be passed
-    around.  There is also a few functions that are used by all the
-    different parameters.
-*/
+/** 
+ * A class to represent the parameter of an extension.
+ *
+ * This is really a super class that allows them to abstract all
+ * the different types of parameters into some that can be passed
+ * around.  There is also a few functions that are used by all the
+ * different parameters.
+ */
 class Parameter {
-private:
-    /** \brief  Which extension is this parameter attached to? */
-    Inkscape::Extension::Extension * extension;
-    /** \brief  The name of this parameter. */
-    gchar *       _name;
 
 protected:
-    /** \brief  Description of the parameter. */
-    gchar *       _desc;
-    /** \brief  List of possible scopes. */
+    /** List of possible scopes. */
     typedef enum {
         SCOPE_USER,     /**<  Parameter value is saved in the user's configuration file. (default) */
         SCOPE_DOCUMENT, /**<  Parameter value is saved in the document. */
         SCOPE_NODE      /**<  Parameter value is attached to the node. */
     } _scope_t;
-    /** \brief  Scope of the parameter. */
+
+public:
+    Parameter(gchar const *name,
+              gchar const *guitext,
+              gchar const *desc,
+              const Parameter::_scope_t scope,
+              bool gui_hidden,
+              gchar const *gui_tip,
+              Inkscape::Extension::Extension * ext);
+
+    Parameter(gchar const *name,
+              gchar const *guitext,
+              Inkscape::Extension::Extension * ext);
+
+    virtual ~Parameter(void);
+
+    /** Wrapper to cast to the object and use its function. */
+    bool get_bool(SPDocument const *doc, Inkscape::XML::Node const *node) const;
+
+    /** Wrapper to cast to the object and use it's function. */
+    int get_int(SPDocument const *doc, Inkscape::XML::Node const *node) const;
+
+    /** Wrapper to cast to the object and use it's function. */
+    float get_float(SPDocument const *doc, Inkscape::XML::Node const *node) const;
+
+    /** Wrapper to cast to the object and use it's function. */
+    gchar const *get_string(SPDocument const *doc, Inkscape::XML::Node const *node) const;
+
+    guint32 get_color(SPDocument const *doc, Inkscape::XML::Node const *node) const;
+
+    /** Wrapper to cast to the object and use it's function. */
+    gchar const *get_enum(SPDocument const *doc, Inkscape::XML::Node const *node) const;
+
+    /** Wrapper to cast to the object and use it's function. */
+    gchar const *get_optiongroup(SPDocument const * doc, Inkscape::XML::Node const *node) const;
+
+
+    /** Wrapper to cast to the object and use it's function. */
+    bool set_bool(bool in, SPDocument * doc, Inkscape::XML::Node * node);
+
+    /** Wrapper to cast to the object and use it's function. */
+    int set_int(int  in, SPDocument * doc, Inkscape::XML::Node * node);
+
+    float set_float(float in, SPDocument * doc, Inkscape::XML::Node * node);
+
+    gchar const *set_optiongroup(gchar const *in, SPDocument * doc, Inkscape::XML::Node *node);
+
+    gchar const *set_string(gchar const * in, SPDocument * doc, Inkscape::XML::Node * node);
+
+    guint32 set_color(guint32 in, SPDocument * doc, Inkscape::XML::Node * node);
+
+    gchar const * name(void) const {return _name;}
+
+    /**
+     * This function creates a parameter that can be used later.  This
+     * is typically done in the creation of the extension and defined
+     * in the XML file describing the extension (it's private so people
+     * have to use the system) :)
+     *
+     * This function first grabs all of the data out of the Repr and puts
+     * it into local variables.  Actually, these are just pointers, and the
+     * data is not duplicated so we need to be careful with it.  If there
+     * isn't a name or a type in the XML, then no parameter is created as
+     * the function just returns.
+     *
+     * From this point on, we're pretty committed as we've allocated an
+     * object and we're starting to fill it.  The name is set first, and
+     * is created with a strdup to actually allocate memory for it.  Then
+     * there is a case statement (roughly because strcmp requires 'ifs')
+     * based on what type of parameter this is.  Depending which type it
+     * is, the value is interpreted differently, but they are relatively
+     * straight forward.  In all cases the value is set to the default
+     * value from the XML and the type is set to the interpreted type.
+     *
+     * @param  in_repr The XML describing the parameter.
+     * @return a pointer to a new Parameter if applicable, null otherwise..
+     */
+    static Parameter *make(Inkscape::XML::Node * in_repr, Inkscape::Extension::Extension * in_ext);
+
+    virtual Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
+
+    gchar const * get_tooltip(void) const { return _desc; }
+
+    /** Indicates if the GUI for this parameter is hidden or not */
+    bool get_gui_hidden() const { return _gui_hidden; }
+
+    virtual void string(std::list <std::string> &list) const;
+
+    /**
+     * Gets the current value of the parameter in a string form.
+     * @return A string with the 'value'.
+     */
+    virtual void string(std::string &string) const;
+
+    /** All the code in Notebook::get_param to get the notebook content. */
+    virtual Parameter *get_param(gchar const *name);
+
+protected:
+    /** Description of the parameter. */
+    gchar *       _desc;
+
+    /** Scope of the parameter. */
     _scope_t _scope;
-    /** \brief  Text for the GUI selection of this. */
+
+    /** Text for the GUI selection of this. */
     gchar *  _text;
-    /** \brief  Whether the GUI is visible */
+
+    /** Whether the GUI is visible. */
     bool _gui_hidden;
-    /** \brief  A tip for the GUI if there is one */
+
+    /** A tip for the GUI if there is one. */
     gchar *  _gui_tip;
 
 
     /* **** funcs **** */
-    gchar *               pref_name (void);
+
+    /**
+     * Build the name to write the parameter from the extension's ID and the name of this parameter.
+     */
+    gchar *pref_name(void) const;
+
     Inkscape::XML::Node * find_child (Inkscape::XML::Node * adult);
+
     Inkscape::XML::Node * document_param_node (SPDocument * doc);
+
     Inkscape::XML::Node * new_child (Inkscape::XML::Node * parent);
 
-public:
-                  Parameter  (const gchar * name,
-                              const gchar * guitext,
-                              const gchar * desc,
-                              const Parameter::_scope_t scope,
-                              bool gui_hidden,
-                              const gchar * gui_tip,
-                              Inkscape::Extension::Extension * ext);
-                  Parameter  (const gchar * name,
-                              const gchar * guitext,
-                              Inkscape::Extension::Extension * ext);
-    virtual      ~Parameter  (void);
-
-    bool          get_bool   (const SPDocument * doc,
-                              const Inkscape::XML::Node * node);
-    int           get_int    (const SPDocument * doc,
-                              const Inkscape::XML::Node * node);
-    float         get_float  (const SPDocument * doc,
-                              const Inkscape::XML::Node * node);
-    const gchar * get_string (const SPDocument * doc,
-                              const Inkscape::XML::Node * node);
-    guint32       get_color  (const SPDocument * doc,
-                              const Inkscape::XML::Node * node);
-    const gchar * get_enum   (const SPDocument * doc,
-                              const Inkscape::XML::Node * node);
-
-    gchar const * get_optiongroup( SPDocument const * doc,
-                                   Inkscape::XML::Node const * node);
-
-    bool          set_bool   (bool in,          SPDocument * doc, Inkscape::XML::Node * node);
-    int           set_int    (int  in,          SPDocument * doc, Inkscape::XML::Node * node);
-    float         set_float  (float in,         SPDocument * doc, Inkscape::XML::Node * node);
-    gchar const * set_optiongroup(gchar const *in, SPDocument * doc, Inkscape::XML::Node *node);
-    const gchar * set_string (const gchar * in, SPDocument * doc, Inkscape::XML::Node * node);
-    guint32       set_color  (guint32 in, SPDocument * doc, Inkscape::XML::Node * node);
-
-    const gchar * name       (void) {return _name;}
-
-    static Parameter * make (Inkscape::XML::Node * in_repr, Inkscape::Extension::Extension * in_ext);
-    virtual Gtk::Widget * get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-
-    gchar const * get_tooltip (void) { return _desc; }
-
-    /** \brief  Indicates if the GUI for this parameter is hidden or not */
-    bool         get_gui_hidden ()   { return _gui_hidden; }
-
-    virtual void string (std::list <std::string> &list);
-    virtual void string (std::string &string);
-
-    virtual Parameter *  get_param  (const gchar * name);
+private:
+    /** Which extension is this parameter attached to. */
+    Inkscape::Extension::Extension *extension;
+
+    /** The name of this parameter. */
+    gchar *_name;
 };
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
 
-#endif /* __INK_EXTENSION_PARAM_H__ */
+#endif // SEEN_INK_EXTENSION_PARAM_H__
 
 /*
   Local Variables:
diff --git a/src/extension/param/radiobutton.cpp b/src/extension/param/radiobutton.cpp
index a805efc7e..a9fcbfd6c 100644
--- a/src/extension/param/radiobutton.cpp
+++ b/src/extension/param/radiobutton.cpp
@@ -35,8 +35,10 @@
 
 #include "radiobutton.h"
 
-/** \brief  The root directory in the preferences database for extension
-            related parameters. */
+/**
+ * The root directory in the preferences database for extension
+ * related parameters.
+ */
 #define PREF_DIR "extensions"
 
 namespace Inkscape {
@@ -136,8 +138,6 @@ ParamRadioButton::ParamRadioButton (const gchar * name,
     if (defaultval != NULL) {
         _value = g_strdup(defaultval);  // allocate space for _value
     }
-
-    return;
 }
 
 ParamRadioButton::~ParamRadioButton (void)
@@ -152,21 +152,22 @@ ParamRadioButton::~ParamRadioButton (void)
 }
 
 
-/** \brief  A function to set the \c _value
-    \param  in   The value to set
-    \param  doc  A document that should be used to set the value.
-    \param  node The node where the value may be placed
-
-    This function sets ONLY the internal value, but it also sets the value
-    in the preferences structure.  To put it in the right place, \c PREF_DIR
-    and \c pref_name() are used.
-
-    To copy the data into _value the old memory must be free'd first.
-    It is important to note that \c g_free handles \c NULL just fine.  Then
-    the passed in value is duplicated using \c g_strdup().
-*/
-const gchar *
-ParamRadioButton::set (const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
+/**
+ * A function to set the \c _value.
+ *
+ * This function sets ONLY the internal value, but it also sets the value
+ * in the preferences structure.  To put it in the right place, \c PREF_DIR
+ * and \c pref_name() are used.
+ *
+ * To copy the data into _value the old memory must be free'd first.
+ * It is important to note that \c g_free handles \c NULL just fine.  Then
+ * the passed in value is duplicated using \c g_strdup().
+ *
+ * @param  in   The value to set.
+ * @param  doc  A document that should be used to set the value.
+ * @param  node The node where the value may be placed.
+ */
+const gchar *ParamRadioButton::set(const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
     if (in == NULL) {
         return NULL; /* Can't have NULL string */
@@ -194,19 +195,12 @@ ParamRadioButton::set (const gchar * in, SPDocument * /*doc*/, Inkscape::XML::No
     return _value;
 }
 
-
-/**
-    \brief  A function to get the current value of the parameter in a string form
-    \return A string with the 'value' as command line argument
-*/
-void
-ParamRadioButton::string (std::string &string)
+void ParamRadioButton::string(std::string &string) const
 {
     string += _value;
-    return;
 }
 
-/** \brief  A special radiobutton class to use in ParamRadioButton */
+/** A special radiobutton class to use in ParamRadioButton. */
 class ParamRadioButtonWdg : public Gtk::RadioButton {
 private:
     ParamRadioButton * _pref;
@@ -214,9 +208,10 @@ private:
     Inkscape::XML::Node * _node;
     sigc::signal<void> * _changeSignal;
 public:
-    /** \brief  Build a string preference for the given parameter
-        \param  pref  Where to put the radiobutton's string when it is selected.
-    */
+    /**
+     * Build a string preference for the given parameter.
+     * @param  pref  Where to put the radiobutton's string when it is selected.
+     */
     ParamRadioButtonWdg ( Gtk::RadioButtonGroup& group, const Glib::ustring& label,
                           ParamRadioButton * pref, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal ) :
         Gtk::RadioButton(group, label), _pref(pref), _doc(doc), _node(node), _changeSignal(changeSignal) {
@@ -233,13 +228,13 @@ public:
     void changed (void);
 };
 
-/** \brief  Respond to the selected radiobutton changing
-
-    This function responds to the radiobutton selection changing by grabbing the value
-    from the text box and putting it in the parameter.
-*/
-void
-ParamRadioButtonWdg::changed (void)
+/**
+ * Respond to the selected radiobutton changing.
+ *
+ * This function responds to the radiobutton selection changing by grabbing the value
+ * from the text box and putting it in the parameter.
+ */
+void ParamRadioButtonWdg::changed(void)
 {
     if (this->get_active()) {
         Glib::ustring data = this->get_label();
@@ -275,10 +270,9 @@ protected:
 };
 
 /**
-    \brief  Creates a combobox widget for an enumeration parameter
-*/
-Gtk::Widget *
-ParamRadioButton::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
+ * Creates a combobox widget for an enumeration parameter.
+ */
+Gtk::Widget * ParamRadioButton::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_gui_hidden) {
         return NULL;
diff --git a/src/extension/param/radiobutton.h b/src/extension/param/radiobutton.h
index cf33bb381..957a5b9df 100644
--- a/src/extension/param/radiobutton.h
+++ b/src/extension/param/radiobutton.h
@@ -6,8 +6,9 @@
  */
 
 /*
- * Author:
+ * Authors:
  *   Johan Engelen <johan@shouraizou.nl>
+ *   Jon A. Cruz <jon@joncruz.org>
  *
  * Copyright (C) 2006-2007 Johan Engelen
  *
@@ -44,10 +45,15 @@ public:
                      AppearanceMode mode);
     virtual ~ParamRadioButton(void);
     Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-    void string (std::string &string);
 
-    const gchar * get (const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) { return _value; }
-    const gchar * set (const gchar * in, SPDocument * doc, Inkscape::XML::Node * node);
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::list <std::string> &list) const { return Parameter::string(list); }
+
+    virtual void string(std::string &string) const;
+
+    const gchar *get(const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) const { return _value; }
+
+    const gchar *set(const gchar *in, SPDocument *doc, Inkscape::XML::Node *node);
 
 private:
     /** \brief  Internal value.  This should point to a string that has
@@ -69,3 +75,13 @@ private:
 
 #endif /* INK_EXTENSION_PARAMRADIOBUTTON_H_SEEN */
 
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
diff --git a/src/extension/param/string.cpp b/src/extension/param/string.cpp
index 18cc754a6..13b8e326a 100644
--- a/src/extension/param/string.cpp
+++ b/src/extension/param/string.cpp
@@ -2,6 +2,7 @@
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -22,27 +23,29 @@ namespace Inkscape {
 namespace Extension {
     
 
-/** \brief  Free the allocated data. */
+/** Free the allocated data. */
 ParamString::~ParamString(void)
 {
     g_free(_value);
+    _value = 0;
 }
 
-/** \brief  A function to set the \c _value
-    \param  in   The value to set to
-    \param  doc  A document that should be used to set the value.
-    \param  node The node where the value may be placed
-
-    This function sets the internal value, but it also sets the value
-    in the preferences structure.  To put it in the right place, \c PREF_DIR
-    and \c pref_name() are used.
-
-    To copy the data into _value the old memory must be free'd first.
-    It is important to note that \c g_free handles \c NULL just fine.  Then
-    the passed in value is duplicated using \c g_strdup().
-*/
-const gchar *
-ParamString::set (const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
+/**
+ * A function to set the \c _value.
+ *
+ * This function sets the internal value, but it also sets the value
+ * in the preferences structure.  To put it in the right place, \c PREF_DIR
+ * and \c pref_name() are used.
+ *
+ * To copy the data into _value the old memory must be free'd first.
+ * It is important to note that \c g_free handles \c NULL just fine.  Then
+ * the passed in value is duplicated using \c g_strdup().
+ *
+ * @param  in   The value to set to.
+ * @param  doc  A document that should be used to set the value.
+ * @param  node The node where the value may be placed.
+ */
+const gchar * ParamString::set(const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
     if (in == NULL) {
         return NULL; /* Can't have NULL string */
@@ -62,18 +65,14 @@ ParamString::set (const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node *
     return _value;
 }
 
-/** \brief  Return the value as a string */
-void
-ParamString::string (std::string &string)
+void ParamString::string(std::string &string) const
 {
-    if (_value == NULL) {
-        return;
+    if (_value) {
+      string += _value;
     }
-    string += _value;
-    return;
 }
 
-/** \brief  Initialize the object, to do that, copy the data. */
+/** Initialize the object, to do that, copy the data. */
 ParamString::ParamString (const gchar * name, const gchar * guitext, const gchar * desc, const Parameter::_scope_t scope, bool gui_hidden, const gchar * gui_tip, Inkscape::Extension::Extension * ext, Inkscape::XML::Node * xml) :
     Parameter(name, guitext, desc, scope, gui_hidden, gui_tip, ext),
               _value(NULL), _indent(0)
@@ -101,11 +100,9 @@ ParamString::ParamString (const gchar * name, const gchar * guitext, const gchar
     }
 
     _max_length = 0;
-
-    return;
 }
 
-/** \brief  A special type of Gtk::Entry to handle string parameteres */
+/** A special type of Gtk::Entry to handle string parameteres. */
 class ParamStringEntry : public Gtk::Entry {
 private:
     ParamString * _pref;
@@ -113,10 +110,11 @@ private:
     Inkscape::XML::Node * _node;
     sigc::signal<void> * _changeSignal;
 public:
-    /** \brief  Build a string preference for the given parameter
-        \param  pref  Where to get the string from, and where to put it
-                      when it changes.
-    */
+    /**
+     * Build a string preference for the given parameter.
+     * @param  pref  Where to get the string from, and where to put it
+     *                when it changes.
+     */
     ParamStringEntry (ParamString * pref, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
         Gtk::Entry(), _pref(pref), _doc(doc), _node(node), _changeSignal(changeSignal) {
         if (_pref->get(NULL, NULL) != NULL) {
@@ -129,31 +127,29 @@ public:
 };
 
 
-/** \brief  Respond to the text box changing
-
-    This function responds to the box changing by grabbing the value
-    from the text box and putting it in the parameter.
-*/
-void
-ParamStringEntry::changed_text (void)
+/**
+ * Respond to the text box changing.
+ *
+ * This function responds to the box changing by grabbing the value
+ * from the text box and putting it in the parameter.
+ */
+void ParamStringEntry::changed_text(void)
 {
     Glib::ustring data = this->get_text();
     _pref->set(data.c_str(), _doc, _node);
     if (_changeSignal != NULL) {
         _changeSignal->emit();
     }
-    return;
 }
 
 /**
-    \brief  Creates a text box for the string parameter
-
-    Builds a hbox with a label and a text box in it.
-*/
-Gtk::Widget *
-ParamString::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
+ * Creates a text box for the string parameter.
+ *
+ * Builds a hbox with a label and a text box in it.
+ */
+Gtk::Widget * ParamString::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
-	if (_gui_hidden) {
+    if (_gui_hidden) {
         return NULL;
     }
 
diff --git a/src/extension/param/string.h b/src/extension/param/string.h
index a1892fe9c..8e7f093f7 100644
--- a/src/extension/param/string.h
+++ b/src/extension/param/string.h
@@ -5,6 +5,7 @@
  * Copyright (C) 2005-2007 Authors:
  *   Ted Gould <ted@gould.cx>
  *   Johan Engelen <johan@shouraizou.nl> *
+ *   Jon A. Cruz <jon@joncruz.org>
  * Released under GNU GPL, read the file 'COPYING' for more information
  */
 
@@ -28,18 +29,26 @@ private:
 public:
     ParamString(const gchar * name, const gchar * guitext, const gchar * desc, const Parameter::_scope_t scope, bool gui_hidden, const gchar * gui_tip, Inkscape::Extension::Extension * ext, Inkscape::XML::Node * xml);
     virtual ~ParamString(void);
+
     /** \brief  Returns \c _value, with a \i const to protect it. */
-    const gchar * get (const SPDocument * /*doc*/, const Inkscape::XML::Node * /*node*/) { return _value; }
+    const gchar *get(SPDocument const * /*doc*/, Inkscape::XML::Node const * /*node*/) const { return _value; }
+
     const gchar * set (const gchar * in, SPDocument * doc, Inkscape::XML::Node * node);
+
     Gtk::Widget * get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal);
-    void string (std::string &string);
+
+    // Explicitly call superclass version to avoid method being hidden.
+    virtual void string(std::list <std::string> &list) const { return Parameter::string(list); }
+
+    virtual void string(std::string &string) const;
+
     void setMaxLength(int maxLenght) { _max_length = maxLenght; }
     int getMaxLength(void) { return _max_length; }
 };
 
 
-}  /* namespace Extension */
-}  /* namespace Inkscape */
+}  // namespace Extension
+}  // namespace Inkscape
 
 #endif /* INK_EXTENSION_PARAMSTRING_H_SEEN */