Re^2: Closure Confusion

Don't confuse creating a closure with compilation. The closure's body is compiled at compile time, not when the closure gets created. The code of this closure says "stringify $j", but which $j is only decided at runtime. Creating a closure at runtime does not compile the code; it merely "connects" it with a specific instance of whichever lexicals it refers to. Since you only create a single $j, all your closures get "connected" to the same $j.

Makeshifts last the longest.

Comment on Re^2: Closure Confusion

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Re: Re^2: Closure Confusion by kabel (Chaplain) on Oct 17, 2002 at 06:54 UTC
thanks to you both for clarification. in fact that is the way things are going. the real problem i think is that the code gets created at compile time. stringification cannot happen since the code has not run yet. so variables stay what they are (even with a hypothetical stringification operator). the same is for the anonymous sub enclosed in an eval (). i could imagine that stringification then works (if only the operator would exist) ... but an eval is expensive, and more than one eval is even more expensive ;)	[reply]
Re^4: Closure Confusion by Aristotle (Chancellor) on Oct 17, 2002 at 12:54 UTC
Oh, `eval` will let you do this: `push @closures, eval "sub { print "\Q$j\E" }";` (Note that if you don't quotemeta the variable, you open yourself up to all sorts of headaches - and a security hole if `$j` contains user input dependent data.) But why would you want that? Just create a unique copy of the lexicals in question during each loop iteration and you'll be fine. There's no reason to resort to `eval STRING` for this job. As all others have already proposed: `my $my_j = $j; push @closures, sub { print $my_j };` [download] Makeshifts last the longest.	[reply] [d/l] [select]
Re: Re^4: Closure Confusion by kabel (Chaplain) on Oct 17, 2002 at 14:32 UTC
i agree with the proposed solution. but thats not the point: the only thing i was interested in was: is it possible? yes, it is; but only with "runtime subroutine compilation". i think this attitude is ... err ... not that welcome here :\|	[reply]