What: apply
Where: http://www.glinx.com/%7Ehclsmith/plugin.html ???
Description: Version of the apply procedure as discussed on
<URL: news:comp.lang.tcl > during February, 1997.
Versions of Tcl C and scripting routines as well as a
lisp-backquote-like proc are available. Now supports Tcl 8.x.
Updated: 09/1999
Contact: mailto:[email protected] (Hume Smith)apply will be a command in 8.5 - see TIP 194 [L1 ] which also gives an illustrative implementation in pure-Tcl.
proc apply {fun args} {
set len [llength $fun]
if {($len < 2) || ($len > 3)} {
error "can't interpret \"$fun\" as anonymous function"
}
lassign $fun argList body ns
set name ::$ns::[getGloballyUniqueName]
set body0 {
rename [lindex [info level 0] 0] {}
}
proc $name $argList ${body0}$body
set code [catch {uplevel 1 $name $args} res opt]
return -options $opt $res
}
RS wonders, however, how the following simpler take is insufficient:
proc apply {fun args} {
foreach {argl body ns} $fun break
namespace eval $ns [list foreach $argl $args break]
namespace eval $ns $body
}Testing:
% apply {x {expr $x*$x}} 5
25
% apply {{x y} {expr hypot($x,$y)} foo} 3 4
5.0NEM The difference is that in your version parameters are persistent namespace variables, rather than local to the procedure. Consider:
% interp alias {} test1 {} apply {x { expr {$x * $x} }}
test1
% interp alias {} test2 {} apply {x { set y [test1 12]; return $x }}
test2
% test2 "Hello!"
12Which isn't what you want, I expect. - RS: Indeed. In fact, I didn't want namespaces at all :) - just because the other version had them... I started with
proc apply {fun args} {
foreach {argl body ns} $fun break
namespace eval $ns [list foreach $argl $args break]
namespace eval $ns $body
}