diff options
Diffstat (limited to 'doc/eval.n')
| -rw-r--r-- | doc/eval.n | 6 |
1 files changed, 5 insertions, 1 deletions
@@ -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: eval.n,v 1.11 2008/06/29 22:28:24 dkf Exp $ +'\" RCS: @(#) $Id: eval.n,v 1.12 2008/10/15 10:43:37 dkf Exp $ '\" .so man.macros .TH eval n "" Tcl "Tcl Built-In Commands" @@ -27,11 +27,13 @@ evaluation (or any error generated by it). Note that the \fBlist\fR command quotes sequences of words in such a way that they are not further expanded by the \fBeval\fR command. .SH EXAMPLES +.PP Often, it is useful to store a fragment of a script in a variable and execute it later on with extra values appended. This technique is used in a number of places throughout the Tcl core (e.g. in \fBfcopy\fR, \fBlsort\fR and \fBtrace\fR command callbacks). This example shows how to do this using core Tcl commands: +.PP .CS set script { puts "logging now" @@ -57,6 +59,7 @@ easier to make robust in practice. The following procedure acts in a way that is analogous to the \fBlappend\fR command, except it inserts the argument values at the start of the list in the variable: +.PP .CS proc lprepend {varName args} { upvar 1 $varName var @@ -66,6 +69,7 @@ proc lprepend {varName args} { set var [\fBeval\fR [list linsert $var 0] $args] } .CE +.PP However, the last line would now normally be written without \fBeval\fR, like this: .CS |