Import Tcl-core 8.6.6 (as of svn r86089)

doc/InitStubs.3

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+'\"
+'\" Copyright (c) 1998-1999 Scriptics Corporation
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\" 
+.TH Tcl_InitStubs 3 8.1 Tcl "Tcl Library Procedures"
+.so man.macros
+.BS
+.SH NAME
+Tcl_InitStubs \- initialize the Tcl stubs mechanism
+.SH SYNOPSIS
+.nf
+\fB#include <tcl.h>\fR
+.sp
+const char *
+\fBTcl_InitStubs\fR(\fIinterp, version, exact\fR)
+.SH ARGUMENTS
+.AS Tcl_Interp *interp
+.AP Tcl_Interp *interp in
+Tcl interpreter handle.
+.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 versions newer than \fIversion\fR are also
+acceptable as long as they have the same major version number
+as \fIversion\fR.
+.BE
+.SH INTRODUCTION
+.PP
+The Tcl stubs mechanism defines a way to dynamically bind
+extensions to a particular Tcl implementation at run time.
+This provides two significant benefits to Tcl users:
+.IP 1) 5
+Extensions that use the stubs mechanism can be loaded into
+multiple versions of Tcl without being recompiled or
+relinked.
+.IP 2) 5
+Extensions that use the stubs mechanism can be dynamically
+loaded into statically-linked Tcl applications.
+.PP
+The stubs mechanism accomplishes this by exporting function tables
+that define an interface to the Tcl API.  The extension then accesses
+the Tcl API through offsets into the function table, so there are no
+direct references to any of the Tcl library's symbols.  This
+redirection is transparent to the extension, so an extension writer
+can continue to use all public Tcl functions as documented.
+.PP
+The stubs mechanism requires no changes to applications incorporating
+Tcl interpreters.  Only developers creating C-based Tcl extensions
+need to take steps to use the stubs mechanism with their extensions.
+.PP
+Enabling the stubs mechanism for an extension requires the following
+steps:
+.IP 1) 5
+Call \fBTcl_InitStubs\fR in the extension before calling any other
+Tcl functions.
+.IP 2) 5
+Define the \fBUSE_TCL_STUBS\fR symbol.  Typically, you would include the
+\fB\-DUSE_TCL_STUBS\fR flag when compiling the extension.
+.IP 3) 5
+Link the extension with the Tcl stubs library instead of the standard
+Tcl library.  For example, to use the Tcl 8.6 ABI on Unix platforms,
+the library name is \fIlibtclstub8.6.a\fR; on Windows platforms, the
+library name is \fItclstub86.lib\fR.
+.PP
+If the extension also requires the Tk API, it must also call
+\fBTk_InitStubs\fR to initialize the Tk stubs interface and link
+with the Tk stubs libraries.  See the \fBTk_InitStubs\fR page for
+more information.
+.SH DESCRIPTION
+\fBTcl_InitStubs\fR attempts to initialize the stub table pointers
+and ensure that the correct version of Tcl is loaded.  In addition
+to an interpreter handle, it accepts as arguments a version number
+and a Boolean flag indicating whether the extension requires
+an exact version match or not.  If \fIexact\fR is 0, then the
+extension is indicating that newer versions of Tcl are acceptable
+as long as they have the same major version number as \fIversion\fR;
+non-zero means that only the specified \fIversion\fR is acceptable.
+\fBTcl_InitStubs\fR returns a string containing the actual version
+of Tcl satisfying the request, or NULL if the Tcl version is not
+acceptable, does not support stubs, or any other error condition occurred.
+.SH "SEE ALSO"
+Tk_InitStubs
+.SH KEYWORDS
+stubs