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author | Kevin B Kenny <kennykb@acm.org> | 2001-05-31 23:45:44 (GMT) |
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committer | Kevin B Kenny <kennykb@acm.org> | 2001-05-31 23:45:44 (GMT) |
commit | f16a9d29ec4b0f401338397dee7f5d24f9acffb5 (patch) | |
tree | fdd7e6cc3e4c627755440c7f60e6ebe4311248fc /doc/catch.n | |
parent | 97464e6cba8eb0008cf2727c15718671992b913f (diff) | |
download | tcl-f16a9d29ec4b0f401338397dee7f5d24f9acffb5.zip tcl-f16a9d29ec4b0f401338397dee7f5d24f9acffb5.tar.gz tcl-f16a9d29ec4b0f401338397dee7f5d24f9acffb5.tar.bz2 |
Development branch for TIPs 22 and 33
kennykb_tip_22_33_botched
Diffstat (limited to 'doc/catch.n')
-rw-r--r-- | doc/catch.n | 70 |
1 files changed, 0 insertions, 70 deletions
diff --git a/doc/catch.n b/doc/catch.n deleted file mode 100644 index 23771f9..0000000 --- a/doc/catch.n +++ /dev/null @@ -1,70 +0,0 @@ -'\" -'\" Copyright (c) 1993-1994 The Regents of the University of California. -'\" Copyright (c) 1994-1996 Sun Microsystems, Inc. -'\" -'\" See the file "license.terms" for information on usage and redistribution -'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. -'\" -'\" RCS: @(#) $Id: catch.n,v 1.3 1999/04/16 00:46:34 stanton Exp $ -'\" -.so man.macros -.TH catch n "8.0" Tcl "Tcl Built-In Commands" -.BS -'\" Note: do not modify the .SH NAME line immediately below! -.SH NAME -catch \- Evaluate script and trap exceptional returns -.SH SYNOPSIS -\fBcatch\fI script \fR?\fIvarName\fR? -.BE - -.SH DESCRIPTION -.PP -The \fBcatch\fR command may be used to prevent errors from aborting command -interpretation. \fBCatch\fR calls the Tcl interpreter recursively to -execute \fIscript\fR, and always returns without raising an error, -regardless of any errors that might occur while executing \fIscript\fR. -.PP -If \fIscript\fR raises an error, \fBcatch\fR will return a non-zero integer -value corresponding to one of the exceptional return codes (see tcl.h -for the definitions of code values). If the \fIvarName\fR argument is -given, then the variable it names is set to the error message from -interpreting \fIscript\fR. -.PP -If \fIscript\fR does not raise an error, \fBcatch\fR will return 0 -(TCL_OK) and set the variable to the value returned from \fIscript\fR. -.PP -Note that \fBcatch\fR catches all exceptions, including those -generated by \fBbreak\fR and \fBcontinue\fR as well as errors. The -only errors that are not caught are syntax errors found when the -script is compiled. This is because the catch command only catches -errors during runtime. When the catch statement is compiled, the -script is compiled as well and any syntax errors will generate a Tcl -error. - -.SH EXAMPLES - -The \fBcatch\fR command may be used in an \fBif\fR to branch based on -the success of a script. - -.DS -.CS -if { [catch {open $someFile w} fid] } { - puts stderr "Could not open $someFile for writing\\n$fid" - exit 1 -} -.CE -.DE -The \fBcatch\fR command will not catch compiled syntax errors. The -first time proc \fBfoo\fR is called, the body will be compiled and a -Tcl error will be generated. - -.DS -.CS -proc foo {} { - catch {expr {1 +- }} -} -.CE -.DE - -.SH KEYWORDS -catch, error |