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authordkf <donal.k.fellows@manchester.ac.uk>2004-05-25 20:42:43 (GMT)
committerdkf <donal.k.fellows@manchester.ac.uk>2004-05-25 20:42:43 (GMT)
commita92bea9824750bfe1962893217f244df483743b6 (patch)
tree61a05640754ba7809dd0a7f58c21f83e6d578623 /doc/close.n
parenta8285cfa1f174bf3040c3c74b408ba979bfe8692 (diff)
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Added example
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diff --git a/doc/close.n b/doc/close.n
index c5d772b..d5ba90b 100644
--- a/doc/close.n
+++ b/doc/close.n
@@ -5,7 +5,7 @@
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: close.n,v 1.5 2004/04/26 14:38:09 dkf Exp $
+'\" RCS: @(#) $Id: close.n,v 1.6 2004/05/25 20:42:43 dkf Exp $
'\"
.so man.macros
.TH close n 7.5 Tcl "Tcl Built-In Commands"
@@ -62,6 +62,21 @@ The command returns an empty string, and may generate an error if
an error occurs while flushing output. If a command in a command
pipeline created with \fBopen\fR returns an error, \fBclose\fR
generates an error (similar to the \fBexec\fR command.)
+.SH EXAMPLE
+This illustrates how you can use Tcl to ensure that files get closed
+even when errors happen by combining \fBcatch\fR, \fBclose\fR and
+\fBreturn\fR:
+.CS
+proc withOpenFile {filename channelVar script} {
+ upvar 1 $channelVar chan
+ set chan [open $filename]
+ catch {
+ uplevel 1 $script
+ } result options
+ close $chan
+ return -options $options $result
+}
+.CE
.SH "SEE ALSO"
file(n), open(n), socket(n), eof(n), Tcl_StandardChannels(3)