Tcl_Main(3)

NAME
Tcl_Main, Tcl_SetMainLoop - main program and event loop definition for Tcl-based applications

SYNOPSIS
#include <tcl.h>

Tcl_Main(argc, argv, appInitProc)

Tcl_SetMainLoop(mainLoopProc)

ARGUMENTS
Number of elements in argv. Array of strings containing command-line arguments. Address of an application-specific initialization procedure. The value for this argument is usually Tcl_AppInit. Address of an application-specific event loop procedure.

DESCRIPTION

Tcl_Main acts as the main program for most Tcl-based applications. Starting with Tcl 7.4 it is not called main anymore because it is part of the Tcl library and having a function main in a library (particularly a shared library) causes problems on many systems. Having main in the Tcl library would also make it hard to use Tcl in C++ programs, since C++ programs must have special C++ main functions.

Normally each application contains a small main function that does nothing but invoke Tcl_Main. Tcl_Main then does all the work of creating and running a tclsh-like application.

When it is has finished its own initialization, but before it processes commands, Tcl_Main calls the procedure given by the appInitProc argument. This procedure provides a ``hook'' for the application to perform its own initialization, such as defining application-specific commands. The procedure must have an interface that matches the type Tcl_AppInitProc:
    typedef int Tcl_AppInitProc(Tcl_Interp *interp);

AppInitProc is almost always a pointer to Tcl_AppInit; for more details on this procedure, see the documentation for Tcl_AppInit. When the appInitProc is finished, the startup script will be evaluated. If none exists, then an interactive prompt is provided.

Tcl_SetMainLoop allows setting an event loop procedure to be run. This allows, for example, Tk to be dynamically loaded and set its event loop. The event loop will run following the startup script. If you are in interactive mode, setting the main loop procedure will cause the prompt to become fileevent based and then the loop procedure is called. The main loop procedure must have an interface that matches the type Tcl_MainLoopProc:
    typedef void Tcl_MainLoopProc(void);

KEYWORDS
application-specific initialization, command-line arguments, main program