allowexc.3

tcl是工具命令语言

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.so man.macros
.TH Tcl_AllowExceptions 3 7.4 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_AllowExceptions \- allow all exceptions in next script evaluation
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
\fBTcl_AllowExceptions\fR(\fIinterp\fR)
.SH ARGUMENTS
.AS Tcl_Interp *doublePtr
.AP Tcl_Interp *interp in
Interpreter in which script will be evaluated.
.BE

.SH DESCRIPTION
.PP
If a script is evaluated at top-level (i.e. no other scripts are
pending evaluation when the script is invoked), and if the script
terminates with a completion code other than TCL_OK, TCL_ERROR
or TCL_RETURN, then Tcl normally converts this into a TCL_ERROR
return with an appropriate message.  The particular script
evaluation procedures of Tcl that act in the manner are
\fBTcl_EvalObjEx\fR, \fBTcl_EvalObjv\fR, \fBTcl_Eval\fR, \fBTcl_EvalEx\fR,
\fBTcl_GlobalEval\fR, \fBTcl_GlobalEvalObj\fR, \fBTcl_VarEval\fR and
\fBTcl_VarEvalVA\fR. 
.PP
However, if \fBTcl_AllowExceptions\fR is invoked immediately before
calling one of those a procedures, then arbitrary completion
codes are permitted from the script, and they are returned without
modification.
This is useful in cases where the caller can deal with exceptions
such as TCL_BREAK or TCL_CONTINUE in a meaningful way.

.SH KEYWORDS
continue, break, exception, interpreter