use explicit virtual keyword with overridden virtual methods

[wxWidgets.git] / docs / latex / wx / module.tex

\section{\class{wxModule}}\label{wxmodule}

The module system is a very simple mechanism to allow applications (and parts
of wxWidgets itself) to define initialization and cleanup functions that are
automatically called on wxWidgets startup and exit.

To define a new kind of module, derive a class from wxModule, override the
\helpref{OnInit}{wxmoduleoninit} and \helpref{OnExit}{wxmoduleonexit} 
functions, and add the DECLARE\_DYNAMIC\_CLASS and IMPLEMENT\_DYNAMIC\_CLASS to
header and implementation files (which can be the same file). On
initialization, wxWidgets will find all classes derived from wxModule, create
an instance of each, and call each OnInit function. On exit, wxWidgets will
call the OnExit function for each module instance.

Note that your module class does not have to be in a header file.

For example:

\begin{verbatim}
  // A module to allow DDE initialization/cleanup
  // without calling these functions from app.cpp or from
  // the user's application.
  class wxDDEModule: public wxModule
  {
  public:
      wxDDEModule() { }
      virtual bool OnInit() { wxDDEInitialize(); return true; };
      virtual void OnExit() { wxDDECleanUp(); };

  private:
      DECLARE_DYNAMIC_CLASS(wxDDEModule)
  };

  IMPLEMENT_DYNAMIC_CLASS(wxDDEModule, wxModule)


  // Another module which uses DDE in its OnInit()
  class MyModule: public wxModule
  {
  public:
      wxDDEModule() { AddDependency(CLASSINFO(wxDDEModule)); }
      virtual bool OnInit() { ... code using DDE ... }
      virtual void OnExit() { ... }

  private:
      DECLARE_DYNAMIC_CLASS(wxDDEModule)
  };
\end{verbatim}

\wxheading{Derived from}

\helpref{wxObject}{wxobject}

\wxheading{Include files}

<wx/module.h>

\latexignore{\rtfignore{\wxheading{Members}}}


\membersection{wxModule::wxModule}\label{wxmodulector}

\func{}{wxModule}{\void}

Constructs a wxModule object.


\membersection{wxModule::\destruct{wxModule}}\label{wxmoduledtor}

\func{}{\destruct{wxModule}}{\void}

Destructor.


\membersection{wxModule::AddDependency}\label{wxmoduleoninit}

\func{void}{AddDependency}{\param{wxClassInfo * }{dep}}

Call this function from the constructor of the derived class. \arg{dep} must be
the \helpref{CLASSINFO}{classinfo} of a wxModule-derived class and the
corresponding module will be loaded \emph{before} and unloaded \emph{after}
this module.

Note that circular dependencies are detected and result in a fatal error.

\wxheading{Parameters}

\docparam{dep}{The class information object for the dependent module.}


\membersection{wxModule::OnExit}\label{wxmoduleonexit}

\func{virtual void}{OnExit}{\void}

Provide this function with appropriate cleanup for your module.


\membersection{wxModule::OnInit}\label{wxmoduleoninit}

\func{virtual bool}{OnInit}{\void}

Provide this function with appropriate initialization for your module. If the function
returns false, wxWidgets will exit immediately.