Runtime Type Information (RTTI)

Detailed Description

wxWidgets uses its own RTTI ("run-time type identification") system which predates the current standard C++ RTTI and so is kept for backwards compatibility reasons but also because it allows some things which the standard RTTI doesn't directly support (such as creating a class from its name).

The standard C++ RTTI can be used in the user code without any problems and in general you shouldn't need to use the functions and the macros in this section unless you are thinking of modifying or adding any wxWidgets classes.

Related Overviews: Runtime Type Information (RTTI)

Related class group: Runtime Type Information (RTTI)

Macros
#define	wxDECLARE_APP(className)
	This is used in headers to create a forward declaration of the wxGetApp() function implemented by wxIMPLEMENT_APP(). More...
#define	wxIMPLEMENT_APP(className)
	This macro defines the application entry point and tells wxWidgets which application class should be used. More...
#define	wxIMPLEMENT_APP_CONSOLE(className)
	This macro defines the application entry point for non-GUI applications and tells wxWidgets which application class should be used. More...
#define	wxIMPLEMENT_WXWIN_MAIN
	This macro defines the application entry point appropriate for the current platform. More...
#define	wxIMPLEMENT_WXWIN_MAIN_CONSOLE
	This macro defines the application entry point for console applications. More...
#define	wxCLASSINFO(className)
	Returns a pointer to the wxClassInfo object associated with this class. More...
#define	wxDECLARE_ABSTRACT_CLASS(className)
	Used inside a class declaration to declare that the class should be made known to the class hierarchy, but objects of this class cannot be created dynamically. More...
#define	wxDECLARE_DYNAMIC_CLASS(className)
	Used inside a class declaration to make the class known to wxWidgets RTTI system and also declare that the objects of this class should be dynamically creatable from run-time type information. More...
#define	wxDECLARE_CLASS(className)
	Used inside a class declaration to declare that the class should be made known to the class hierarchy, but objects of this class cannot be created dynamically. More...
#define	wxIMPLEMENT_ABSTRACT_CLASS(className, baseClassName)
	Used in a C++ implementation file to complete the declaration of a class that has run-time type information. More...
#define	wxIMPLEMENT_ABSTRACT_CLASS2(className, baseClassName1, baseClassName2)
	Used in a C++ implementation file to complete the declaration of a class that has run-time type information and two base classes. More...
#define	wxIMPLEMENT_DYNAMIC_CLASS(className, baseClassName)
	Used in a C++ implementation file to complete the declaration of a class that has run-time type information, and whose instances can be created dynamically. More...
#define	wxIMPLEMENT_DYNAMIC_CLASS2(className, baseClassName1, baseClassName2)
	Used in a C++ implementation file to complete the declaration of a class that has run-time type information, and whose instances can be created dynamically. More...
#define	wxIMPLEMENT_CLASS(className, baseClassName)
	Synonym for wxIMPLEMENT_ABSTRACT_CLASS(). More...
#define	wxIMPLEMENT_CLASS2(className, baseClassName1, baseClassName2)
	Synonym for wxIMPLEMENT_ABSTRACT_CLASS2(). More...
#define	wx_truncate_cast(T, x)
	This case doesn’t correspond to any standard cast but exists solely to make casts which possibly result in a truncation of an integer value more readable. More...
#define	wxConstCast(ptr, classname)
	This macro expands into const_cast<classname *>(ptr) if the compiler supports const_cast or into an old, C-style cast, otherwise. More...
#define	wxDynamicCast(ptr, classname)
	This macro returns the pointer ptr cast to the type classname * if the pointer is of this type (the check is done during the run-time) or NULL otherwise. More...
#define	wxDynamicCastThis(classname)
	This macro is equivalent to wxDynamicCast(this, classname) but the latter provokes spurious compilation warnings from some compilers (because it tests whether this pointer is non-NULL which is always true), so this macro should be used to avoid them. More...
#define	wxStaticCast(ptr, classname)
	This macro checks that the cast is valid in debug mode (an assert failure will result if wxDynamicCast(ptr, classname) == NULL) and then returns the result of executing an equivalent of static_cast<classname *>(ptr). More...
#define	wxGetVariantCast(var, classname)
	This macro returns a pointer to the data stored in var (wxVariant) cast to the type classname if the data is of this type (the check is done during the run-time) or NULL otherwise. More...

Functions
wxObject *	wxCreateDynamicObject (const wxString &className)
	Creates and returns an object of the given class, if the class has been registered with the dynamic class system using DECLARE... More...

Macro Definition Documentation

wx_truncate_cast

#define wx_truncate_cast	(		T,
			x
	)

This case doesn’t correspond to any standard cast but exists solely to make casts which possibly result in a truncation of an integer value more readable.

Include file:

#include <wx/defs.h> 

wxCLASSINFO

#define wxCLASSINFO

(

className

)

Returns a pointer to the wxClassInfo object associated with this class.

Include file:

#include <wx/object.h> 

wxConstCast

#define wxConstCast	(		ptr,
			classname
	)

This macro expands into const_cast<classname *>(ptr) if the compiler supports const_cast or into an old, C-style cast, otherwise.

Include file:

#include <wx/defs.h> 

See also

wxDynamicCast(), wxStaticCast()

wxDECLARE_ABSTRACT_CLASS

#define wxDECLARE_ABSTRACT_CLASS

(

className

)

Used inside a class declaration to declare that the class should be made known to the class hierarchy, but objects of this class cannot be created dynamically.

Include file:

#include <wx/object.h> 

Example:

class wxCommand: public wxObject
{
    wxDECLARE_ABSTRACT_CLASS(wxCommand);
 
private:
    ...
public:
    ...
};

wxDECLARE_APP

#define wxDECLARE_APP

(

className

)

This is used in headers to create a forward declaration of the wxGetApp() function implemented by wxIMPLEMENT_APP().

It creates the declaration className& wxGetApp() (requires a final semicolon).

Include file:

#include <wx/app.h> 

Example:

wxDECLARE_APP(MyApp);

wxDECLARE_CLASS

#define wxDECLARE_CLASS

(

className

)

Used inside a class declaration to declare that the class should be made known to the class hierarchy, but objects of this class cannot be created dynamically.

The same as wxDECLARE_ABSTRACT_CLASS().

Include file:

#include <wx/object.h> 

wxDECLARE_DYNAMIC_CLASS

#define wxDECLARE_DYNAMIC_CLASS

(

className

)

Used inside a class declaration to make the class known to wxWidgets RTTI system and also declare that the objects of this class should be dynamically creatable from run-time type information.

Notice that this implies that the class should have a default constructor, if this is not the case consider using wxDECLARE_ABSTRACT_CLASS().

Include file:

#include <wx/object.h> 

Example:

class wxFrame: public wxWindow
{
    wxDECLARE_DYNAMIC_CLASS(wxFrame);
 
private:
    const wxString& frameTitle;
public:
    ...
};

wxDynamicCast

#define wxDynamicCast	(		ptr,
			classname
	)

This macro returns the pointer ptr cast to the type classname * if the pointer is of this type (the check is done during the run-time) or NULL otherwise.

Usage of this macro is preferred over obsoleted wxObject::IsKindOf() function.

The ptr argument may be NULL, in which case NULL will be returned.

Include file:

#include <wx/object.h> 

Example:

wxWindow *win = wxWindow::FindFocus();
wxTextCtrl *text = wxDynamicCast(win, wxTextCtrl);
if ( text )
{
    // a text control has the focus...
}
else
{
    // no window has the focus or it is not a text control
}

See also

Runtime Type Information (RTTI), wxDynamicCastThis(), wxConstCast(), wxStaticCast()

wxDynamicCastThis

#define wxDynamicCastThis

(

classname

)

This macro is equivalent to wxDynamicCast(this, classname) but the latter provokes spurious compilation warnings from some compilers (because it tests whether this pointer is non-NULL which is always true), so this macro should be used to avoid them.

Include file:

#include <wx/object.h> 

See also

wxDynamicCast()

wxGetVariantCast

#define wxGetVariantCast	(		var,
			classname
	)

This macro returns a pointer to the data stored in var (wxVariant) cast to the type classname if the data is of this type (the check is done during the run-time) or NULL otherwise.

Include file:

#include <wx/variant.h> 

See also

Runtime Type Information (RTTI), wxDynamicCast()

wxIMPLEMENT_ABSTRACT_CLASS

#define wxIMPLEMENT_ABSTRACT_CLASS	(		className,
			baseClassName
	)

Used in a C++ implementation file to complete the declaration of a class that has run-time type information.

Include file:

#include <wx/object.h> 

Example:

wxIMPLEMENT_ABSTRACT_CLASS(wxCommand, wxObject);
 
wxCommand::wxCommand()
{
    ...
}

wxIMPLEMENT_ABSTRACT_CLASS2

#define wxIMPLEMENT_ABSTRACT_CLASS2	(		className,
			baseClassName1,
			baseClassName2
	)

Used in a C++ implementation file to complete the declaration of a class that has run-time type information and two base classes.

Include file:

#include <wx/object.h> 

wxIMPLEMENT_APP

#define wxIMPLEMENT_APP

(

className

)

This macro defines the application entry point and tells wxWidgets which application class should be used.

The two tasks performed by this macro can be done separately by using wxIMPLEMENT_APP_NO_MAIN() and wxIMPLEMENT_WXWIN_MAIN() macros, but in a typical GUI application it's simpler and more convenient to use this macro to do both together.

The className passed to this macro must be a name of the class deriving from wxApp.

Note that this macro requires a final semicolon.

Include file:

#include <wx/app.h> 

Example:

wxIMPLEMENT_APP(MyApp);

See also

wxDECLARE_APP(), wxIMPLEMENT_APP_CONSOLE()

wxIMPLEMENT_APP_CONSOLE

#define wxIMPLEMENT_APP_CONSOLE

(

className

)

This macro defines the application entry point for non-GUI applications and tells wxWidgets which application class should be used.

This macro is provided for symmetry with wxIMPLEMENT_APP() for the console (non-GUI) applications and is equivalent to using wxIMPLEMENT_APP_NO_MAIN() and wxIMPLEMENT_WXWIN_MAIN_CONSOLE().

The className passed to this macro must be a name of the class deriving from wxApp.

Note that this macro requires a final semicolon.

Include file:

#include <wx/app.h> 

Example:

wxIMPLEMENT_APP_CONSOLE(MyApp);

See also

wxIMPLEMENT_APP()

wxIMPLEMENT_CLASS

#define wxIMPLEMENT_CLASS	(		className,
			baseClassName
	)

Synonym for wxIMPLEMENT_ABSTRACT_CLASS().

Please prefer to use the more clear, if longer, wxIMPLEMENT_ABSTRACT_CLASS in the new code.

Include file:

#include <wx/object.h> 

wxIMPLEMENT_CLASS2

#define wxIMPLEMENT_CLASS2	(		className,
			baseClassName1,
			baseClassName2
	)

Synonym for wxIMPLEMENT_ABSTRACT_CLASS2().

Please prefer to use the more clear, if longer, wxIMPLEMENT_ABSTRACT_CLASS2 in the new code.

Include file:

#include <wx/object.h> 

wxIMPLEMENT_DYNAMIC_CLASS

#define wxIMPLEMENT_DYNAMIC_CLASS	(		className,
			baseClassName
	)

Used in a C++ implementation file to complete the declaration of a class that has run-time type information, and whose instances can be created dynamically.

Include file:

#include <wx/object.h> 

Example:

wxIMPLEMENT_DYNAMIC_CLASS(wxFrame, wxWindow);
 
wxFrame::wxFrame()
{
    ...
}

wxIMPLEMENT_DYNAMIC_CLASS2

#define wxIMPLEMENT_DYNAMIC_CLASS2	(		className,
			baseClassName1,
			baseClassName2
	)

Used in a C++ implementation file to complete the declaration of a class that has run-time type information, and whose instances can be created dynamically.

Use this for classes derived from two base classes.

Include file:

#include <wx/object.h> 

wxIMPLEMENT_WXWIN_MAIN

#define wxIMPLEMENT_WXWIN_MAIN

This macro defines the application entry point appropriate for the current platform.

Note that usually wxIMPLEMENT_APP() is used instead of this macro.

For most platforms, it defines main() function, but for GUI Windows applications, it defines WinMain() instead.

In either case, the macro expansion includes the call to wxDISABLE_DEBUG_SUPPORT() which disables debugging code in release builds. If you don't use this macro, but define the entry point yourself, you probably want to call wxDISABLE_DEBUG_SUPPORT() explicitly.

Include file:

#include <wx/app.h> 

wxIMPLEMENT_WXWIN_MAIN_CONSOLE

#define wxIMPLEMENT_WXWIN_MAIN_CONSOLE

This macro defines the application entry point for console applications.

This macro is provided mostly for symmetry with wxIMPLEMENT_WXWIN_MAIN() but is less useful, as it is also simple enough to define main() function directly.

Please note, however, that this macro, as well as wxIMPLEMENT_APP_CONSOLE() which uses it, contains the call to wxDISABLE_DEBUG_SUPPORT() which disables debugging code in release builds and that if you don't use this macro, but define main() yourself, you probably want to call wxDISABLE_DEBUG_SUPPORT() from it explicitly.

Include file:

#include <wx/app.h> 

wxStaticCast

#define wxStaticCast	(		ptr,
			classname
	)

This macro checks that the cast is valid in debug mode (an assert failure will result if wxDynamicCast(ptr, classname) == NULL) and then returns the result of executing an equivalent of static_cast<classname *>(ptr).

Include file:

#include <wx/object.h> 

See also

wxDynamicCast(), wxConstCast()

Function Documentation

wxCreateDynamicObject()

wxObject* wxCreateDynamicObject

(

const wxString &

className

)

Creates and returns an object of the given class, if the class has been registered with the dynamic class system using DECLARE...

and IMPLEMENT... macros.

Include file:

#include <wx/object.h>