diff options
Diffstat (limited to 'doc/SaveResult.3')
-rw-r--r-- | doc/SaveResult.3 | 109 |
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 |