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# critcl::literals(n) 1.1 doc "C Runtime In Tcl (CriTcl)"

## Name

critcl::literals - CriTcl Utilities: Constant string pools

## Table Of Contents

## Synopsis

- package require Tcl 8.4
- package require critcl ?3.1.11?
- package require critcl::literals ?1.1?

- ::critcl::literals::def name definition

## Description

Welcome to the C Runtime In Tcl, CriTcl for short, a system to build C extension packages for Tcl on the fly, from C code embedded within Tcl scripts, for all who wish to make their code go faster.

This document is the reference manpage for the critcl::literals package. This package provides convenience commands for advanced functionality built on top of both critcl core and package critcl::iassoc.

Many packages will have a fixed set of string constants occuring in one or places. Most of them will be coded to create a new string Tcl_Obj* from a C char* every time the constant is needed, as this is easy to to, despite the inherent waste of memory.

This package was written to make declaration and management of string pools which do not waste memory as easy as the wasteful solution, hiding all attendant complexity from the user.

Its intended audience are mainly developers wishing to write Tcl packages with embedded C code.

This package resides in the Core Package Layer of CriTcl.

## API

::critcl::literals::def name definition

  This command defines a C function with the given name which provides access to a pool of constant strings with a Tcl interpreter.

  The definition dictionary provides the mapping from the C-level symbolic names to the string themselves.

  The new function has two parameters, a Tcl_Interp* pointer refering to the interpreter holding the string pool, and a code of type "name_names" (see below), the symbolic name of the literal to return. Tcl result of the function is a Tcl_Obj* pointer to the requested string constant.

  The underlying string pool is automatically initialized on first access, and finalized on interpreter destruction.

  The package generates multiple things (declarations and definitions) with names derived from name, which has to be a proper C identifier.

  name

    The function providing access to the string pool. Its signature is

        Tcl_Obj* name (Tcl_Interp* interp, name_names literal);

  name_names

    A C enumeration type containing the symbolic names of the strings provided by the pool.

  name.h

    A header file containing the declarations for the accessor function and enumeration type, for use by other parts of the system, if necessary.

    The generated file is stored in a place where it will not interfere with the overall system outside of the package, yet also be available for easy inclusion by package files (csources).

  name

    New in version 1.1: At the level of critcl itself the command registers a new result-type for critcl::cproc, which takes an integer result from the function and converts it to the equivalent string in the pool for the script.

## Example

The example shown below is the specification of the string pool pulled from the draft work on a Tcl binding to Linux's inotify APIs.

    package require Tcl 8.5
    package require critcl 3.1.11
    critcl::buildrequirement {
        package require critcl::literals
    }
    critcl::literals::def tcl_inotify_strings {
        w_create	"create"
        w_directory	"directory"
        w_events	"events"
        w_file	"file"
        w_handler	"handler"
        w_remove	"remove"
    }
    # Declarations: tcl_inotify_strings.h
    # Type:         tcl_inotify_strings_names
    # Accessor:     Tcl_Obj* tcl_inotify_strings (Tcl_Interp*               interp,
    #                                             tcl_inotify_strings_names literal);
    # ResultType:   tcl_inotify_strings

## Authors

Andreas Kupries

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such at https://github.com/andreas-kupries/critcl. Please also report any ideas for enhancements you may have for either package and/or documentation.

## Keywords

C code, Embedded C Code, Tcl Interp Association, code generator, compile & run, compiler, dynamic code generation, dynamic compilation, generate package, linker, literal pool, on demand compilation, on-the-fly compilation, singleton, string pool

## Category

Glueing/Embedded C code

## Copyright

Copyright © 2011-2015 Andreas Kupries