NewClass - adding a new class to wxPerl
Are there constants or events that need to be wrapped?
see "CONSTANTS" and "EVENTS".
Is the class is derived from wxObject, from wxEvtHandler or from another class?
see "CHOOSING A TYPEMAP".
Are class instances destroyed by wxWidgets or should they be garbage collected like normal Perl objects?
see "DESTRUCTORS AND THREADS".
Does the class have overloaded methods?
see "OVERLOADING".
Does the class have virtual methods that should be overridable from Perl?
see "VIRTUAL METHODS".
Add a new file XS/NewClass.xsp and update the MANIFEST. Choose a relevant .xs file in the top level directory (eg. Controls.xs) and add this line:
INCLUDE_COMMAND: $^X -MExtUtils::XSpp::Cmd -e xspp -- -t typemap.xsp XS/NewClass.xsp
A skeleton for NewClass.xsp:
%module{Wx}; #include <wx/newclass.h> // use the relevant wxWidgets header(s) %name{Wx::NewClass} class wxNewClass : public wxSomeBaseClass { # constructors see the CONSTRUCTORS section wxNewClass( wxWindow* some_window, const wxString& str ); # destructors ~wxNewClass(); # methods wxString GetString() const; void SetString( const wxString& str ); };
Add the typemap definition to typemap.tmpl. See "CHOOSING A TYPEMAP".
If adding a class related to one of the wxPerl submodules (Wx::RichText, Wx::Html, ...) add the .xsp file to the relevant subdirectory and modify the .xs and typemap files in that subdirectory.
Wx::RichText
Wx::Html
There are five typemaps that should work for most wxWidgets objects:
O_NON_WXOBJECT
for all classes that do not derive from wxObject AND do not need to be garbage collected.
wxObject
O_NON_WXOBJECT_THR
for all classes that do not derive from wxObject AND need to be garbage collected (see "DESTRUCTORS AND THREADS").
O_WXOBJECT
for all classes that derive from wxObject AND do not need to be garbage collected.
O_WXOBJECT_THR
for all classes derived from wxObject AND need to be garbage collected (see "DESTRUCTORS AND THREADS").
O_WXEVTHANDLER
for all classes that derive from wxEvtHandler. See also "CONSTRUCTORS".
wxEvtHandler
For O_WXEVTHANDLER typemaps, there is some additional code that needs to be added to the constructor:
wxNewClass( wxWindow* some_window, const wxString& str ) %code{% RETVAL = new wxNewClass( some_window, str ); wxPli_create_evthandler( aTHX_ RETVAL, CLASS ); %};
For many classes not derived from wxEvtHandler you need to add a destructor to free the C++ object when the Perl object is garbage collected. At the XS++ level this means adding
~wxNewClass();
to the class definition, but there is a catch: the Perl threading model.
Without going into details, this is needed for Perl threads compatibility:
Use the correct typemap
choose either O_NON_WXOBJECT_THR or O_WXOBJECT_THR.
Implement a CLONE method
CLONE
add this code inside the class declaration:
%{ static void wxNewClass::CLONE() CODE: wxPli_thread_sv_clone( aTHX_ CLASS, (wxPliCloneSV)wxPli_detach_object ); %}
Fix the destructor.
modify the destructor like this:
~wxNewClass() %code%{ wxPli_thread_sv_unregister( aTHX_ "Wx::NewClass", THIS, ST(0) ); delete THIS; %};
The wrapping of virtual functions whose arguments are simple C++ types (integrals, bool, floating point) and common wxWidgets types (wxString) should be automatic: at the top of the file, load the plugin that handles virtual methods
%loadplugin{build::Wx::XSP::Virtual};
and decorate virtual/pure virtual methods using the %Virtual directive
%Virtual
// pure virtual virtual wxString GetTitle() const = 0 %Virtual{pure}; // virtual, not pure virtual int GetBestFittingWidth(unsigned int idx) const %Virtual;
If the class contains pure virtual methods, it will be marked as abstract, and it will have no constructors.
For abstract classes, XS++ will create an additional Perl-level class, called Wx::Pl<classname>; in order to override the virtual methods, you must derive from this class, and not from Wx::<classname>.
Wx::Pl<classname>
Wx::<classname>
TODO allow changing the default behaviour for abstract/concrete classes
TODO allow overriding the class name
TODO allow specifying custom code
TODO handle multiple return values
TODO customized type mapping
To install Wx, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Wx
CPAN shell
perl -MCPAN -e shell install Wx
For more information on module installation, please visit the detailed CPAN module installation guide.