critcl_enum3tcl

Usage

Overview

Be welcome to the C Runtime In Tcl (short: CriTcl), a system for embedding and using C code from within Tcl [http://core.tcl-lang.org/tcl] scripts.

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

It is an extended form of string pool which not only converts integer values into Tcl-level strings, but also handles the reverse direction, converting from strings to the associated integer values.

It essentially provides a bi-directional mapping between a C enumeration type and a set of strings, one per enumeration value. Note that the C enumeration in question is created by the definition. It is not possible to use the symbols of an existing enumeration type.

This package was written to make the declaration and management of such mappings easy. It uses a string pool for one of the directions, using its ability to return shared literals and conserve memory.

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.

+----------------+
|Applications    |
| critcl         |
| critcl::app    |
+----------------+
*================*
|Core Packages   |
| critcl         |
| critcl::util   |
*================*
+----------------+
|Support Packages|
| stubs::*       |
| md5, platform  |
|  ...           |
+----------------+

API

::critcl::enum::def name definition ?mode?

This command defines two C functions for the conversion between C values and Tcl_Obj'ects, with named derived from name.

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

The mode-list configures the output somewhat. The two allowed modes are +list and tcl. All modes can be used together. The default mode is tcl. Using mode +list implies tcl as well.

For mode tcl the new function has two arguments, a Tcl_Interp* pointer refering to the interpreter holding the string pool, and a code of type "name_pool_names" (see below), the symbolic name of the string to return. The result of the function is a Tcl_Obj* pointer to the requested string constant.

For mode +list all of tcl applies, plus an additional function is generated which takes three arguments, in order: a Tcl_Interp* pointer refering to the interpreter holding the string pool, an int holding the size of the last argument, and an array of type "name_pool_names" holding the codes (see below), the symbolic names of the strings to return. The result of the function is a Tcl_Obj* pointer to a Tcl list holding the requested string constants.

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_pool_names

The C enumeration type containing the specified symbolic names.

name_ToObj

The function converting from integer value to Tcl string. Its signature is

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

name_ToObjList

The mode +list function converting from integer array to Tcl list of strings. Its signature is

Tcl_Obj* name_ToObjList (Tcl_Interp* interp, int c, name_names* literal);

name_GetFromObj

The function converting from Tcl string to integer value. Its signature is

int name_GetFromObj (Tcl_Interp* interp, Tcl_Obj* obj, int flags, int* literal);

The flags are like for Tcl_GetIndexFromObj.

name.h

A header file containing the declarations for the converter functions, 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

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.

name

At the level of critcl itself the command registers a new argument-type for critcl::cproc, which takes a Tcl string and converts it to the equivalent integer for delivery to the function.

Examples

The example shown below is the specification for a set of actions, methods, and the like, a function may take as argument.

package require Tcl 8.6
package require critcl 3.2
critcl::buildrequirement {
    package require critcl::enum
}
critcl::enum::def action {
    w_create	"create"
    w_directory	"directory"
    w_events	"events"
    w_file	"file"
    w_handler	"handler"
    w_remove	"remove"
}
# Declarations: action.h
# Type:         action_names
# Accessor:     Tcl_Obj* action_ToObj (Tcl_Interp* interp, int literal);
# Accessor:     int action_GetFromObj (Tcl_Interp* interp, Tcl_Obj* o, int flags, int* literal);
# ResultType:   action
# ArgType:      action

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, conversion, dynamic code generation, dynamic compilation, generate package, int to string mapping, linker, literal pool, on demand compilation, on-the-fly compilation, singleton, string pool, string to int mapping

Category

Glueing/Embedded C code