Non-destructive substitution?

Sprad has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Non-destructive substitution? by Abigail (Deacon) on Jul 03, 2001 at 01:16 UTC
You cannot avoid using a different variable. The usual idiom is: `($tmp = $string) =~ s/foo/blah/;` [download] If you want to combine it with calling a function, use Perls `do`: `func do {(my $tmp = $string) =~ s/foo/blah; $tmp};` [download] Or `func do {local $_ = $string; s/foo/blah; $_};` [download] -- Abigail	[reply] [d/l] [select]
Re: Re: Non-destructive substitution? by MeowChow (Vicar) on Jul 03, 2001 at 01:27 UTC
Such a shame too, it would be nice if there were a "return substituted copy" modifer for `s///`, would make alot of golfs shorter :) MeowChow s aamecha.s a..a\u$&owag.print	[reply]
Re: Non-destructive substitution? by epoptai (Curate) on Jul 03, 2001 at 01:17 UTC
There is a cleaner way, but you still need the temporary variable to preserve $string. I assume you need $string later which is the only reason you'd need a non-destructive substitution. You can declare and substitute in one step: `(my$tmp = $string) =~ s/foo/blah/;` [download] -- Check out my Perlmonks Related Scripts like framechat, reputer, and xNN.	[reply] [d/l]
Re: Non-destructive substitution? by CharlesClarkson (Curate) on Jul 03, 2001 at 08:02 UTC
A similar question was answered on c.l.p.misc in May. The solution is not mine, but I present it here. Wanted: function composition using tr, s, etc. operators: `$var2 = s/123/456/g (tr/a-z/A-Z/ ($var));` [download] The answer: `sub apply (&$) { local $_ = $_[1]; $_[0]->(); $_; } $var2 = apply {s/123/456/g; tr/a-z/A-Z/} $var;` [download] or in this case: `$string = apply {s/foo/blah/} $string;` HTH, Charles K. Clarkson	[reply] [d/l] [select]
Re: Re: Non-destructive substitution? by bobione (Pilgrim) on Jul 03, 2001 at 15:32 UTC
I am not sure that this function "apply()" is shorter or more usefull than a temporary variable... :) BobiOne KenoBi ;)	[reply]
Re: Non-destructive substitution? by CharlesClarkson (Curate) on Jul 04, 2001 at 14:41 UTC
Probably not, but it may be what was requested: "a cleaner way to do that, preferably without having to use a temporary variable each time". TIMTOWTDI, Charles K. Clarkson	[reply]