[OpenSPARC-T2-SAM] / sam-t2 / devtools / amd64 / man / man3 / Tcl_DeleteInterp.3

'\"
'\" Copyright (c) 1989-1993 The Regents of the University of California.
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'\" RCS: @(#) $Id: CrtInterp.3,v 1.7 2002/06/26 11:50:52 msofer Exp $
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'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
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.AS Tcl_Interp Tcl_CreateInterp in/out
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.TH Tcl_CreateInterp 3 7.5 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_CreateInterp, Tcl_DeleteInterp, Tcl_InterpDeleted \- create and delete Tcl command interpreters
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
Tcl_Interp *
\fBTcl_CreateInterp\fR()
.sp
\fBTcl_DeleteInterp\fR(\fIinterp\fR)
.sp
int
\fBTcl_InterpDeleted\fR(\fIinterp\fR)
.SH ARGUMENTS
.AS Tcl_Interp *interp
.AP Tcl_Interp *interp in
Token for interpreter to be destroyed.
.BE

.SH DESCRIPTION
.PP
\fBTcl_CreateInterp\fR creates a new interpreter structure and returns
a token for it.  The token is required in calls to most other Tcl
procedures, such as \fBTcl_CreateCommand\fR, \fBTcl_Eval\fR, and
\fBTcl_DeleteInterp\fR.
Clients are only allowed to access a few of the fields of
Tcl_Interp structures;  see the \fBTcl_Interp\fR
and \fBTcl_CreateCommand\fR man pages for details.
The new interpreter is initialized with the built-in Tcl commands
and with the variables documented in tclvars(n).  To bind in
additional commands, call \fBTcl_CreateCommand\fR.
.PP
\fBTcl_DeleteInterp\fR marks an interpreter as deleted; the interpreter
will eventually be deleted when all calls to \fBTcl_Preserve\fR for it have
been matched by calls to \fBTcl_Release\fR. At that time, all of the
resources associated with it, including variables, procedures, and
application-specific command bindings, will be deleted.  After
\fBTcl_DeleteInterp\fR returns any attempt to use \fBTcl_Eval\fR on the
interpreter will fail and return \fBTCL_ERROR\fR. After the call to
\fBTcl_DeleteInterp\fR it is safe to examine the interpreter's result,
query or set the values of variables, define, undefine or retrieve
procedures, and examine the runtime evaluation stack. See below, in the
section \fBINTERPRETERS AND MEMORY MANAGEMENT\fR for details.
.PP
\fBTcl_InterpDeleted\fR returns nonzero if \fBTcl_DeleteInterp\fR was
called with \fIinterp\fR as its argument; this indicates that the
interpreter will eventually be deleted, when the last call to
\fBTcl_Preserve\fR for it is matched by a call to \fBTcl_Release\fR. If
nonzero is returned, further calls to \fBTcl_Eval\fR in this interpreter
will return \fBTCL_ERROR\fR.
.PP
\fBTcl_InterpDeleted\fR is useful in deletion callbacks to distinguish
between when only the memory the callback is responsible for is being
deleted and when the whole interpreter is being deleted. In the former case
the callback may recreate the data being deleted, but this would lead to an
infinite loop if the interpreter were being deleted.

.SH "INTERPRETERS AND MEMORY MANAGEMENT"
.PP
\fBTcl_DeleteInterp\fR can be called at any time on an interpreter that may
be used by nested evaluations and C code in various extensions. Tcl
implements a simple mechanism that allows callers to use interpreters
without worrying about the interpreter being deleted in a nested call, and
without requiring special code to protect the interpreter, in most cases.
This mechanism ensures that nested uses of an interpreter can safely
continue using it even after \fBTcl_DeleteInterp\fR is called.
.PP
The mechanism relies on matching up calls to \fBTcl_Preserve\fR with calls
to \fBTcl_Release\fR. If \fBTcl_DeleteInterp\fR has been called, only when
the last call to \fBTcl_Preserve\fR is matched by a call to
\fBTcl_Release\fR, will the interpreter be freed. See the manual entry for
\fBTcl_Preserve\fR for a description of these functions.
.PP
The rules for when the user of an interpreter must call \fBTcl_Preserve\fR
and \fBTcl_Release\fR are simple:
.TP
Interpreters Passed As Arguments
Functions that are passed an interpreter as an argument can safely use the
interpreter without any special protection. Thus, when you write an
extension consisting of new Tcl commands, no special code is needed to
protect interpreters received as arguments. This covers the majority of all
uses.
.TP
Interpreter Creation And Deletion
When a new interpreter is created and used in a call to \fBTcl_Eval\fR,
\fBTcl_VarEval\fR, \fBTcl_GlobalEval\fR, \fBTcl_SetVar\fR, or
\fBTcl_GetVar\fR, a pair of calls to \fBTcl_Preserve\fR and
\fBTcl_Release\fR should be wrapped around all uses of the interpreter.
Remember that it is unsafe to use the interpreter once \fBTcl_Release\fR
has been called. To ensure that the interpreter is properly deleted when
it is no longer needed, call \fBTcl_InterpDeleted\fR to test if some other
code already called \fBTcl_DeleteInterp\fR; if not, call
\fBTcl_DeleteInterp\fR before calling \fBTcl_Release\fR in your own code.
.TP
Retrieving An Interpreter From A Data Structure
When an interpreter is retrieved from a data structure (e.g. the client
data of a callback) for use in \fBTcl_Eval\fR, \fBTcl_VarEval\fR,
\fBTcl_GlobalEval\fR, \fBTcl_SetVar\fR, or \fBTcl_GetVar\fR, a pair of
calls to \fBTcl_Preserve\fR and \fBTcl_Release\fR should be wrapped around
all uses of the interpreter; it is unsafe to reuse the interpreter once
\fBTcl_Release\fR has been called.  If an interpreter is stored inside a
callback data structure, an appropriate deletion cleanup mechanism should
be set up by the code that creates the data structure so that the
interpreter is removed from the data structure (e.g. by setting the field
to NULL) when the interpreter is deleted. Otherwise, you may be using an
interpreter that has been freed and whose memory may already have been
reused.
.PP
All uses of interpreters in Tcl and Tk have already been protected.
Extension writers should ensure that their code also properly protects any
additional interpreters used, as described above.

.SH "SEE ALSO"
Tcl_Preserve(3), Tcl_Release(3)

.SH KEYWORDS
command, create, delete, interpreter
Commit	Line	Data
920dae64 AT	1	'\"
	2	'\" Copyright (c) 1989-1993 The Regents of the University of California.
	3	'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
	4	'\"
	5	'\" See the file "license.terms" for information on usage and redistribution
	6	'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
	7	'\"
	8	'\" RCS: @(#) $Id: CrtInterp.3,v 1.7 2002/06/26 11:50:52 msofer Exp $
	9	'\"
	10	'\" The definitions below are for supplemental macros used in Tcl/Tk
	11	'\" manual entries.
	12	'\"
	13	'\" .AP type name in/out ?indent?
	14	'\" Start paragraph describing an argument to a library procedure.
	15	'\" type is type of argument (int, etc.), in/out is either "in", "out",
	16	'\" or "in/out" to describe whether procedure reads or modifies arg,
	17	'\" and indent is equivalent to second arg of .IP (shouldn't ever be
	18	'\" needed; use .AS below instead)
	19	'\"
	20	'\" .AS ?type? ?name?
	21	'\" Give maximum sizes of arguments for setting tab stops. Type and
	22	'\" name are examples of largest possible arguments that will be passed
	23	'\" to .AP later. If args are omitted, default tab stops are used.
	24	'\"
	25	'\" .BS
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74	.if t .wh -1.3i ^B
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107	..
108	.AS Tcl_Interp Tcl_CreateInterp in/out
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245	..
246	.TH Tcl_CreateInterp 3 7.5 Tcl "Tcl Library Procedures"
247	.BS
248	.SH NAME
249	Tcl_CreateInterp, Tcl_DeleteInterp, Tcl_InterpDeleted \- create and delete Tcl command interpreters
250	.SH SYNOPSIS
251	.nf
252	\fB#include <tcl.h>\fR
253	.sp
254	Tcl_Interp *
255	\fBTcl_CreateInterp\fR()
256	.sp
257	\fBTcl_DeleteInterp\fR(\fIinterp\fR)
258	.sp
259	int
260	\fBTcl_InterpDeleted\fR(\fIinterp\fR)
261	.SH ARGUMENTS
262	.AS Tcl_Interp *interp
263	.AP Tcl_Interp *interp in
264	Token for interpreter to be destroyed.
265	.BE
266
267	.SH DESCRIPTION
268	.PP
269	\fBTcl_CreateInterp\fR creates a new interpreter structure and returns
270	a token for it. The token is required in calls to most other Tcl
271	procedures, such as \fBTcl_CreateCommand\fR, \fBTcl_Eval\fR, and
272	\fBTcl_DeleteInterp\fR.
273	Clients are only allowed to access a few of the fields of
274	Tcl_Interp structures; see the \fBTcl_Interp\fR
275	and \fBTcl_CreateCommand\fR man pages for details.
276	The new interpreter is initialized with the built-in Tcl commands
277	and with the variables documented in tclvars(n). To bind in
278	additional commands, call \fBTcl_CreateCommand\fR.
279	.PP
280	\fBTcl_DeleteInterp\fR marks an interpreter as deleted; the interpreter
281	will eventually be deleted when all calls to \fBTcl_Preserve\fR for it have
282	been matched by calls to \fBTcl_Release\fR. At that time, all of the
283	resources associated with it, including variables, procedures, and
284	application-specific command bindings, will be deleted. After
285	\fBTcl_DeleteInterp\fR returns any attempt to use \fBTcl_Eval\fR on the
286	interpreter will fail and return \fBTCL_ERROR\fR. After the call to
287	\fBTcl_DeleteInterp\fR it is safe to examine the interpreter's result,
288	query or set the values of variables, define, undefine or retrieve
289	procedures, and examine the runtime evaluation stack. See below, in the
290	section \fBINTERPRETERS AND MEMORY MANAGEMENT\fR for details.
291	.PP
292	\fBTcl_InterpDeleted\fR returns nonzero if \fBTcl_DeleteInterp\fR was
293	called with \fIinterp\fR as its argument; this indicates that the
294	interpreter will eventually be deleted, when the last call to
295	\fBTcl_Preserve\fR for it is matched by a call to \fBTcl_Release\fR. If
296	nonzero is returned, further calls to \fBTcl_Eval\fR in this interpreter
297	will return \fBTCL_ERROR\fR.
298	.PP
299	\fBTcl_InterpDeleted\fR is useful in deletion callbacks to distinguish
300	between when only the memory the callback is responsible for is being
301	deleted and when the whole interpreter is being deleted. In the former case
302	the callback may recreate the data being deleted, but this would lead to an
303	infinite loop if the interpreter were being deleted.
304
305	.SH "INTERPRETERS AND MEMORY MANAGEMENT"
306	.PP
307	\fBTcl_DeleteInterp\fR can be called at any time on an interpreter that may
308	be used by nested evaluations and C code in various extensions. Tcl
309	implements a simple mechanism that allows callers to use interpreters
310	without worrying about the interpreter being deleted in a nested call, and
311	without requiring special code to protect the interpreter, in most cases.
312	This mechanism ensures that nested uses of an interpreter can safely
313	continue using it even after \fBTcl_DeleteInterp\fR is called.
314	.PP
315	The mechanism relies on matching up calls to \fBTcl_Preserve\fR with calls
316	to \fBTcl_Release\fR. If \fBTcl_DeleteInterp\fR has been called, only when
317	the last call to \fBTcl_Preserve\fR is matched by a call to
318	\fBTcl_Release\fR, will the interpreter be freed. See the manual entry for
319	\fBTcl_Preserve\fR for a description of these functions.
320	.PP
321	The rules for when the user of an interpreter must call \fBTcl_Preserve\fR
322	and \fBTcl_Release\fR are simple:
323	.TP
324	Interpreters Passed As Arguments
325	Functions that are passed an interpreter as an argument can safely use the
326	interpreter without any special protection. Thus, when you write an
327	extension consisting of new Tcl commands, no special code is needed to
328	protect interpreters received as arguments. This covers the majority of all
329	uses.
330	.TP
331	Interpreter Creation And Deletion
332	When a new interpreter is created and used in a call to \fBTcl_Eval\fR,
333	\fBTcl_VarEval\fR, \fBTcl_GlobalEval\fR, \fBTcl_SetVar\fR, or
334	\fBTcl_GetVar\fR, a pair of calls to \fBTcl_Preserve\fR and
335	\fBTcl_Release\fR should be wrapped around all uses of the interpreter.
336	Remember that it is unsafe to use the interpreter once \fBTcl_Release\fR
337	has been called. To ensure that the interpreter is properly deleted when
338	it is no longer needed, call \fBTcl_InterpDeleted\fR to test if some other
339	code already called \fBTcl_DeleteInterp\fR; if not, call
340	\fBTcl_DeleteInterp\fR before calling \fBTcl_Release\fR in your own code.
341	.TP
342	Retrieving An Interpreter From A Data Structure
343	When an interpreter is retrieved from a data structure (e.g. the client
344	data of a callback) for use in \fBTcl_Eval\fR, \fBTcl_VarEval\fR,
345	\fBTcl_GlobalEval\fR, \fBTcl_SetVar\fR, or \fBTcl_GetVar\fR, a pair of
346	calls to \fBTcl_Preserve\fR and \fBTcl_Release\fR should be wrapped around
347	all uses of the interpreter; it is unsafe to reuse the interpreter once
348	\fBTcl_Release\fR has been called. If an interpreter is stored inside a
349	callback data structure, an appropriate deletion cleanup mechanism should
350	be set up by the code that creates the data structure so that the
351	interpreter is removed from the data structure (e.g. by setting the field
352	to NULL) when the interpreter is deleted. Otherwise, you may be using an
353	interpreter that has been freed and whose memory may already have been
354	reused.
355	.PP
356	All uses of interpreters in Tcl and Tk have already been protected.
357	Extension writers should ensure that their code also properly protects any
358	additional interpreters used, as described above.
359
360	.SH "SEE ALSO"
361	Tcl_Preserve(3), Tcl_Release(3)
362
363	.SH KEYWORDS
364	command, create, delete, interpreter