# dynfunc.h | documentation

    #charset "us-ascii"
    #pragma once

    /*
     *   Copyright (c) 2000, 2006 Michael J. Roberts
     *
     *   This file is part of TADS 3.
     *
     *   The header defines the DynamicFunc intrinsic class.  This class is used
     *   for creating new functions from source code strings dynamically at
     *   run-time.
     *
     *   Programs that use the DynamicFunc class should add the system library
     *   source file dynfunc.t to the build file list, since it contains some
     *   additional definitions that are useful with this class.
     */

    /* include our base class definitions */
    #include "systype.h"

    /*
     *   The DynamicFunc class is used to create new functions from source code
     *   strings dynamically at run-time.  To create a new executable function,
     *   create a new DynamicFunc object:
     *
     *.    local f = new DynamicFunc('function(x) { return x*2; }',
     *.                              globals, locals, macros);
     *
     *   The first constructor argument is a string giving the source code to
     *   compile.
     *
     *   The optional second argument is a LookupTable containing the global
     *   symbols for the compilation.  This can be the table returned from
     *   t3GetGlobalSymbols(), or it can be a custom table.  The compiler looks
     *   up string keys in the table to resolve global symbol names; the
     *   corresponding values can be objects, properties, enum values, or
     *   function pointers.
     *
     *   The optional third argument is a StackFrameDesc object, or a list of
     *   StackFrameDesc objects, giving the stack frames to use for local
     *   variable access within the dynamic code.  The source code can refer to
     *   local variables in these frames, and can assign new values to them.
     *   This is analogous to the way anonymous functions can refer to local
     *   variables in their lexically enclosing scopes.  If you supply a list,
     *   the compiler searches the frames in order of their appearance in the
     *   list.  If a variable appears in more than one frame in the list, the
     *   compiler will use the first occurrence it finds.
     *
     *   The optional fourth argument is a LookupTable giving the preprocessor
     *   macros to use for the compilation.  This is a table in the format
     *   returned by t3GetGlobalsSymbols(T3PreprocMacros).
     *
     *   If the 'symtab' or 'macros' arguments are omitted or nil, the
     *   compilation is done without global symbols or macros, respectively.
     *   Note that built-in functions and intrinsic classes are identified by
     *   global symbols, so you won't be able to call any built-ins if you don't
     *   provide a symbol table.
     *
     *   The source code string can start with the keyword 'function', followed
     *   by a list of parameter names, followed by the executable statements in
     *   braces.  Or, it can simply be a list of statements, in which case it's a
     *   function with no arguments, as though it started with 'function()'.
     *
     *   Creating a DynamicFunc compiles the source code.  If a compilation error
     *   occurs (such as a syntax error, or an unknown symbol reference), the
     *   'new' call will throw a CompilerException error.  The exception object
     *   contains information on the specific compiler error.
     *
     *   To invoke the new function, simply use the standard function call syntax
     *   on the object value, as though it were a regular function pointer:
     *
     *.     local y = f(7);
     */
    intrinsic class DynamicFunc 'dynamic-func/030000'
    {
        /*
         *   Get the original source code of the function.  This returns the
         *   string that was used as the source string to create the function.
         */
        getSource();
    }

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