DOKK / manpages / debian 11 / tcl8.6-doc / Tcl_AppInit.3tcl.en
Tcl_AppInit(3tcl) Tcl Library Procedures Tcl_AppInit(3tcl) 







Tcl_AppInit - perform application-specific initialization








#include <tcl.h>

int
Tcl_AppInit(interp)









  
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:



  
[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.

  
[4]

  
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.










Tcl_Main(3tcl)










application, argument, command, initialization, interpreter







  

    7.0
    Tcl