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-rw-r--r--doc/SaveResult.3109
1 files changed, 37 insertions, 72 deletions
diff --git a/doc/SaveResult.3 b/doc/SaveResult.3
index 6dd6cb6..1ddc1ad 100644
--- a/doc/SaveResult.3
+++ b/doc/SaveResult.3
@@ -1,6 +1,7 @@
'\"
'\" Copyright (c) 1997 by Sun Microsystems, Inc.
'\" Contributions from Don Porter, NIST, 2004. (not subject to US copyright)
+'\" Copyright (c) 2018 Nathan Coulter.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
@@ -9,7 +10,9 @@
.so man.macros
.BS
.SH NAME
-Tcl_SaveInterpState, Tcl_RestoreInterpState, Tcl_DiscardInterpState, Tcl_SaveResult, Tcl_RestoreResult, Tcl_DiscardResult \- save and restore an interpreter's state
+Tcl_SaveInterpState, Tcl_RestoreInterpState, Tcl_DiscardInterpState,
+Tcl_SaveResult, Tcl_RestoreResult, Tcl_DiscardResult \- Save and restore the
+state of an an interpreter.
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
@@ -30,91 +33,53 @@ int
.SH ARGUMENTS
.AS Tcl_InterpState savedPtr
.AP Tcl_Interp *interp in
-Interpreter for which state should be saved.
+The current interpreter.
.AP int status in
-Return code value to save as part of interpreter state.
+The return code for the state.
.AP Tcl_InterpState state in
-Saved state token to be restored or discarded.
+A token for saved state.
.AP Tcl_SavedResult *savedPtr in
-Pointer to location where interpreter result should be saved or restored.
+A pointer to storage for saved state.
.BE
.SH DESCRIPTION
.PP
-These routines allows a C procedure to take a snapshot of the current
-state of an interpreter so that it can be restored after a call
-to \fBTcl_Eval\fR or some other routine that modifies the interpreter
-state. There are two triplets of routines meant to work together.
+These routines save the state of an interpreter before a call to a routine such
+as \fBTcl_Eval\fR, and restore the state afterwards.
.PP
-The first triplet stores the snapshot of interpreter state in
-an opaque token returned by \fBTcl_SaveInterpState\fR. That token
-value may then be passed back to one of \fBTcl_RestoreInterpState\fR
-or \fBTcl_DiscardInterpState\fR, depending on whether the interp
-state is to be restored. So long as one of the latter two routines
-is called, Tcl will take care of memory management.
+\fBTcl_SaveInterpState\fR saves the parts of \fIinterp\fR that comprise the
+result of a script, including the resulting value, the return code passed as
+\fIstatus\fR, and any options such as \fB\-errorinfo\fR and \fB\-errorcode\fR.
+It returns a token for the saved state. The interpreter result is not reset
+and no interpreter state is changed.
.PP
-The second triplet stores the snapshot of only the interpreter
-result (not its complete state) in memory allocated by the caller.
-These routines are passed a pointer to \fBTcl_SavedResult\fR
-that is used to store enough information to restore the interpreter result.
-\fBTcl_SavedResult\fR can be allocated on the stack of the calling
-procedure. These routines do not save the state of any error
-information in the interpreter (e.g. the \fB\-errorcode\fR or
-\fB\-errorinfo\fR return options, when an error is in progress).
+\fBTcl_RestoreInterpState\fR restores the state indicated by \fIstate\fR and
+returns the \fIstatus\fR originally passed in the corresponding call to
+\fBTcl_SaveInterpState\fR.
.PP
-Because the routines \fBTcl_SaveInterpState\fR,
-\fBTcl_RestoreInterpState\fR, and \fBTcl_DiscardInterpState\fR perform
-a superset of the functions provided by the other routines,
-any new code should only make use of the more powerful routines.
-The older, weaker routines \fBTcl_SaveResult\fR, \fBTcl_RestoreResult\fR,
-and \fBTcl_DiscardResult\fR continue to exist only for the sake
-of existing programs that may already be using them.
+If a saved state is not restored, \fBTcl_DiscardInterpState\fR must be called
+to release it. A token used to discard or restore state must not be used
+again.
.PP
-\fBTcl_SaveInterpState\fR takes a snapshot of those portions of
-interpreter state that make up the full result of script evaluation.
-This include the interpreter result, the return code (passed in
-as the \fIstatus\fR argument, and any return options, including
-\fB\-errorinfo\fR and \fB\-errorcode\fR when an error is in progress.
-This snapshot is returned as an opaque token of type \fBTcl_InterpState\fR.
-The call to \fBTcl_SaveInterpState\fR does not itself change the
-state of the interpreter. Unlike \fBTcl_SaveResult\fR, it does
-not reset the interpreter.
+\fBTcl_SaveResult\fR, \fBTcl_RestoreResult\fR, and \fBTcl_DiscardResult\fR are
+deprecated. Instead use \fBTcl_SaveInterpState\fR,
+\fBTcl_RestoreInterpState\fR, and \fBTcl_DiscardInterpState\fR, which are more
+capable.
.PP
-\fBTcl_RestoreInterpState\fR accepts a \fBTcl_InterpState\fR token
-previously returned by \fBTcl_SaveInterpState\fR and restores the
-state of the interp to the state held in that snapshot. The return
-value of \fBTcl_RestoreInterpState\fR is the status value originally
-passed to \fBTcl_SaveInterpState\fR when the snapshot token was
-created.
+\fBTcl_SaveResult\fR moves the string result and structured result of
+\fIinterp\fR to the location \fIstatePtr\fR points to and returns the
+interpreter result to its initial state. It does not save options such as
+\fB\-errorcode\fR or \fB\-errorinfo\fR.
.PP
-\fBTcl_DiscardInterpState\fR is called to release a \fBTcl_InterpState\fR
-token previously returned by \fBTcl_SaveInterpState\fR when that
-snapshot is not to be restored to an interp.
+\fBTcl_RestoreResult\fR clears any existing result or error in \fIinterp\fR and
+moves the string result and structured result from \fIstatePtr\fR back to
+\fIinterp\fR. \fIstatePtr\fR is then in an undefined state and cannot be used
+until passed again to \fBTcl_SaveResult\fR.
.PP
-The \fBTcl_InterpState\fR token returned by \fBTcl_SaveInterpState\fR
-must eventually be passed to either \fBTcl_RestoreInterpState\fR
-or \fBTcl_DiscardInterpState\fR to avoid a memory leak. Once
-the \fBTcl_InterpState\fR token is passed to one of them, the
-token is no longer valid and should not be used anymore.
-.PP
-\fBTcl_SaveResult\fR moves the string and value results
-of \fIinterp\fR into the location specified by \fIstatePtr\fR.
-\fBTcl_SaveResult\fR clears the result for \fIinterp\fR and
-leaves the result in its normal empty initialized state.
-.PP
-\fBTcl_RestoreResult\fR moves the string and value results from
-\fIstatePtr\fR back into \fIinterp\fR. Any result or error that was
-already in the interpreter will be cleared. The \fIstatePtr\fR is left
-in an uninitialized state and cannot be used until another call to
-\fBTcl_SaveResult\fR.
-.PP
-\fBTcl_DiscardResult\fR releases the saved interpreter state
-stored at \fBstatePtr\fR. The state structure is left in an
-uninitialized state and cannot be used until another call to
+\fBTcl_DiscardResult\fR releases the state stored at \fBstatePtr\fR, which is
+then in an undefined state and cannot be used until passed again to
\fBTcl_SaveResult\fR.
.PP
-Once \fBTcl_SaveResult\fR is called to save the interpreter
-result, either \fBTcl_RestoreResult\fR or
-\fBTcl_DiscardResult\fR must be called to properly clean up the
-memory associated with the saved state.
+If a saved result is not restored, \fBTcl_DiscardResult\fR must be called to
+release it.
.SH KEYWORDS
result, state, interp