bionic (3) Tcl_AppInit.3tcl.gz

NAME

       Tcl_AppInit - perform application-specific initialization

SYNOPSIS

       #include <tcl.h>

       int
       Tcl_AppInit(interp)

ARGUMENTS

       Tcl_Interp *interp (in)          Interpreter for the application.
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DESCRIPTION

       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:

       [1]    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
              initialization.

       [2]    Process  command-line  arguments,  which  can be accessed from the Tcl variables argv and argv0 in
              interp.

       [3]    Invoke a startup script to initialize the application.

       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.

KEYWORDS

       application, argument, command, initialization, interpreter