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Diffstat (limited to 'doc/subst.n')
| -rw-r--r-- | doc/subst.n | 44 |
1 files changed, 38 insertions, 6 deletions
diff --git a/doc/subst.n b/doc/subst.n index 36884eb..b76a70c 100644 --- a/doc/subst.n +++ b/doc/subst.n @@ -1,11 +1,12 @@ '\" '\" Copyright (c) 1994 The Regents of the University of California. '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. +'\" Copyright (c) 2001 Donal K. Fellows '\" '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: subst.n,v 1.3 2000/09/07 14:27:51 poenitz Exp $ +'\" RCS: @(#) $Id: subst.n,v 1.4 2001/07/12 13:15:09 dkf Exp $ '\" .so man.macros .TH subst n 7.4 Tcl "Tcl Built-In Commands" @@ -35,17 +36,48 @@ For example, if \fB\-nocommands\fR is specified, no command substitution is performed: open and close brackets are treated as ordinary characters with no special interpretation. .PP -Note: when it performs its substitutions, \fIsubst\fR does not -give any special treatment to double quotes or curly braces. For -example, the script +.VS 8.4 +If a break exception occurs during the evaluation of a command +substitution, the result of the substitution will be the string (as +substituted) up to the start of the command substitution. If a +continue exception occurs during the evaluation of a command +substitution, an empty string will be substituted for that entire +command substitution (as long as it is well-formed Tcl.) +.VE +.SH EXAMPLES +.PP +When it performs its substitutions, \fIsubst\fR does not give any +special treatment to double quotes or curly braces (except within +command substitutions) so the script .CS \fBset a 44 subst {xyz {$a}}\fR .CE -returns ``\fBxyz {44}\fR'', not ``\fBxyz {$a}\fR''. +returns ``\fBxyz {44}\fR'', not ``\fBxyz {$a}\fR'' +.VS 8.4 +and the script +.CS +\fBset a "p\\} q \\{r" +subst {xyz {$a}}\fR +.CE +return ``\fBxyz {p} q {r}\fR'', not ``\fBxyz {p\\} q \\{r}\fR''. +.PP +The continue and break exceptions allow command substitutions to +prevent substitution of the rest of the command substitution and the +rest of \fIstring\fR respectively, giving script authors more options +when processing text using \fIsubst\fR. For example, the script +.CS +\fBsubst {abc,[break],def}\fR +.CE +returns ``\fBabc,\fR'', not ``\fBabc,,def\fR'' and the script +.CS +\fBsubst {abc,[continue;expr 1+2],def}\fR +.CE +returns ``\fBabc,,def\fR'', not ``\fBabc,3,def\fR''. +.VE .SH "SEE ALSO" -eval(n) +Tcl(n), eval(n), break(n), continue(n) .SH KEYWORDS backslash substitution, command substitution, variable substitution |