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Tcl_AppInit(3) Tcl Library Procedures Tcl_AppInit(3)
Tcl_AppInit - perform application-specific initialization
Tcl_Interp *interp (in) Interpreter for the application.
Tcl_AppInit is a "hook" procedure that is invoked by the main programs
for Tcl applications such as tclsh and wish. Its purpose is to allow
new Tcl applications to be created without modifying the main programs
provided as part of Tcl and Tk. To create a new application you write
a new version of Tcl_AppInit to replace the default version provided by
Tcl, then link your new Tcl_AppInit with the Tcl library.
Tcl_AppInit is invoked by Tcl_Main and Tk_Main after their own
initialization and before entering the main loop to process commands.
Here are some examples of things that Tcl_AppInit might do:
 Call initialization procedures for various packages used by the
application. Each initialization procedure adds new commands to
interp for its package and performs other package-specific
 Process command-line arguments, which can be accessed from the
Tcl variables argv and argv0 in interp.
 Invoke a startup script to initialize the application.
 Use the routines Tcl_SetStartupScript and Tcl_GetStartupScript
to set or query the file and encoding that the active Tcl_Main
or Tk_Main routine will use as a startup script.
Tcl_AppInit returns TCL_OK or TCL_ERROR. If it returns TCL_ERROR then
it must leave an error message in for the interpreter's result;
otherwise the result is ignored.
In addition to Tcl_AppInit, your application should also contain a
procedure main that calls Tcl_Main as follows:
Tcl_Main(argc, argv, Tcl_AppInit);
The third argument to Tcl_Main gives the address of the application-
specific initialization procedure to invoke. This means that you do
not have to use the name Tcl_AppInit for the procedure, but in practice
the name is nearly always Tcl_AppInit (in versions before Tcl 7.4 the
name Tcl_AppInit was implicit; there was no way to specify the
procedure explicitly). The best way to get started is to make a copy
of the file tclAppInit.c from the Tcl library or source directory. It
already contains a main procedure and a template for Tcl_AppInit that
you can modify for your application.
application, argument, command, initialization, interpreter
Tcl 7.0 Tcl_AppInit(3)