'\"
'\" Copyright (c) 1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: PkgRequire.3,v 1.6 2002/02/26 02:22:20 hobbs Exp $
'\" 
.so man.macros
.TH Tcl_PkgRequire 3 7.5 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_PkgRequire, Tcl_PkgRequireEx, Tcl_PkgPresent, Tcl_PkgPresentEx, Tcl_PkgProvide, Tcl_PkgProvideEx \- package version control
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
CONST char *
\fBTcl_PkgRequire\fR(\fIinterp, name, version, exact\fR)
.sp
CONST char *
\fBTcl_PkgRequireEx\fR(\fIinterp, name, version, exact, clientDataPtr\fR)
.sp
CONST char *
\fBTcl_PkgPresent\fR(\fIinterp, name, version, exact\fR)
.sp
CONST char *
\fBTcl_PkgPresentEx\fR(\fIinterp, name, version, exact, clientDataPtr\fR)
.sp
int
\fBTcl_PkgProvide\fR(\fIinterp, name, version\fR)
.sp
int
\fBTcl_PkgProvideEx\fR(\fIinterp, name, version, clientData\fR)
.SH ARGUMENTS
.AS ClientData clientDataPtr
.AP Tcl_Interp *interp in
Interpreter where package is needed or available.
.AP "CONST char" *name in
Name of package.
.AP "CONST char" *version in
A version string consisting of one or more decimal numbers
separated by dots.
.AP int exact in
Non-zero means that only the particular version specified by
\fIversion\fR is acceptable.
Zero means that newer versions than \fIversion\fR are also
acceptable as long as they have the same major version number
as \fIversion\fR.
.AP ClientData clientData in
Arbitrary value to be associated with the package.
.AP ClientData *clientDataPtr out
Pointer to place to store the value associated with the matching
package. It is only changed if the pointer is not NULL and the
function completed successfully.
.BE

.SH DESCRIPTION
.PP
These procedures provide C-level interfaces to Tcl's package and
version management facilities.
.PP
\fBTcl_PkgRequire\fR is equivalent to the \fBpackage require\fR
command, \fBTcl_PkgPresent\fR is equivalent to the \fBpackage present\fR
command, and \fBTcl_PkgProvide\fR is equivalent to the
\fBpackage provide\fR command.
.PP
See the documentation for the Tcl commands for details on what these
procedures do.
.PP
If \fBTcl_PkgPresent\fR or \fBTcl_PkgRequire\fR complete successfully
they return a pointer to the version string for the version of the package
that is provided in the interpreter (which may be different than 
\fIversion\fR); if an error occurs they return NULL and leave an error 
message in the interpreter's result.
.PP
\fBTcl_PkgProvide\fR returns TCL_OK if it completes successfully;
if an error occurs it returns TCL_ERROR and leaves an error message
in the interpreter's result.
.PP
\fBTcl_PkgProvideEx\fR, \fBTcl_PkgPresentEx\fR and \fBTcl_PkgRequireEx\fR
allow the setting and retrieving of the client data associated with
the package. In all other respects they are equivalent to the matching
functions.

.SH KEYWORDS
package, present, provide, require, version