saveresult.3

tcl是工具命令语言

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.so man.macros
.TH Tcl_SaveResult 3 8.1 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_SaveResult, Tcl_RestoreResult, Tcl_DiscardResult \- save and restore an interpreter's result
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
\fBTcl_SaveResult(\fIinterp, statePtr\fB)\fR
.sp
\fBTcl_RestoreResult(\fIinterp, statePtr\fB)\fR
.sp
\fBTcl_DiscardResult(\fIstatePtr\fB)\fR
.SH ARGUMENTS
.AS Tcl_SavedResult statePtr
.AP Tcl_Interp *interp in
Interpreter for which state should be saved.
.AP Tcl_SavedResult *statePtr in
Pointer to location where interpreter result should be saved or restored.
.BE

.SH DESCRIPTION
.PP
These routines allows a C procedure to take a snapshot of the current
interpreter result so that it can be restored after a call
to \fBTcl_Eval\fR or some other routine that modifies the interpreter
result.  These routines are passed a pointer to a structure that is
used to store enough information to restore the interpreter result
state.  This structure 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 \fBerrorCode\fR or
\fBerrorInfo\fR variables).
.PP
\fBTcl_SaveResult\fR moves the string and object 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 object 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_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.  

.SH KEYWORDS
result, state, interp