ICI Modules: tcl

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Modules by name : by type

Overview

This module unites ICI and Tk/Tcl. The module provides an interface to allow ICI programs to create instances of Tcl interpreters, issue commands within those interpreters and read/write variables. In addition it provides Tcl with an ici command to invoke the ICI parser. These two abilities may be used to allow communications between the portions of the program written in Tcl and those written in ICI. It is especially useful when used in conjunction with Tk allowing Tk's event handling to invoke ICI functions.

The module is no longer actively developed. It's intended purpose was to provide access to the Tk toolkit and as other toolkits provide better facilities this interest has waned.

Introduction

ICI-Tcl is an interface between ICI and Tk/Tcl. ICI-Tcl is both an ICI
extension that lets ICI call the Tcl interpreter and a Tcl command
that allows Tcl to call ICI. ICI-Tcl adds a "tcl_interp" type to ICI
and a number of functions for evaluating Tcl code. It also adds an
"ici" command to Tcl that allows Tcl code to call upon ICI.


The ICI-Tcl interface is,

	tcp_interp = tcl.Interpreter()

	    Create and return a new Tcl interpreter object for use in
	    subsequent calls to Eval, GlobalEval or EvalFile.

	string = tcl.Eval([interpreter,] string)
	string = tcl.GlobalEval([interpreter,] string)
	string = tcl.EvalFile([interpreter,] string)

	    Evaluate Tcl code and return the result. The nature of
	    evaluation depends on the actual function being called and
	    controls how the string parameter is used. Eval and
	    GlobalEval evaluate code directly and the string contains
	    Tcl code. EvalFile evalulates the content of a file and
	    the string is the name of the file containing the Tcl
	    program to be evaluated.

	string = tcl.GetVar([interpreter,] string [, string] [, "global" ])

	    Get the value of a Tcl variable with the given name.
	    If the name is given in two separate arguments the first
	    must be the name of a Tcl array variable and the second
	    string is the index.

	    If interpreter is not given the default interpreter
	    is used. If the last parameter is the string "global"
	    then only the Tcl global level is searched.

	string = tcl.GetVar2([interpreter,] string, string [, "global" ])

	    A hack until GetVar can be rewritten.

	tcl.SetVar([interpreter, ] name [, name2] , value)

	    Set the Tcl variable, or array element if two names are
	    given, to the value. Use the default interpreter if none
	    is given in the call.

	tcl.Tk_MainLoop()

	    Calls Tk's event processing loop.


Tcl's ICI command.

ICI-Tcl/Tk adds a new command to the interpreters it creates. The
"ici" command takes a single parameter, a string containing ICI code
to be parsed, and calls the ICI interpreter to run it. The result of
the command is the empty string.

To call ICI from Tcl you do something like,

	ici "printf(\"Hello, World!\\n\");"

Note how the ICI code is in a Tcl string and any "funny" characters
need escaping so they survive the Tcl parser.


Exchanging data between ICI and Tcl.

To set a Tcl variable from ICI you need to evaluate a Tcl
expression,

	tcl.Eval("set a foobar");

This could be wrapped in an ICI function as,

	static tcl_set_variable(name, value)
	{
	    tcl.Eval("set " + name + string(value));
	}

And used as,

	tcl_set_variable("toggle_underlines", 1);

Note that tcl_set_variable() calls string() to turn the value object
into a string as necessary.

To obtain the value of a Tcl variable you also use tcl.Eval() to
perform a "set" command but this time you use the output,

	printf("%s\n", tcl.Eval("set a"));

This, of course, can be wrapped in an ICI function,

	static tcl_get_variable(name)
	{
	    return tcl.Eval("set " + name);
	}