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How can I expand variables in text strings?

by faq_monk (Initiate)
on Oct 08, 1999 at 00:20 UTC ( #605=perlfaq nodetype: print w/replies, xml ) Need Help??

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

Let's assume that you have a string like:

    $text = 'this has a $foo in it and a $bar';

If those were both global variables, then this would suffice:

    $text =~ s/\$(\w+)/${$1}/g;

But since they are probably lexicals, or at least, they could be, you'd have to do this:

    $text =~ s/(\$\w+)/$1/eeg;
    die if $@;                  # needed on /ee, not /e

It's probably better in the general case to treat those variables as entries in some special hash. For example:

    %user_defs = ( 
        foo  => 23,
        bar  => 19,
    );
    $text =~ s/\$(\w+)/$user_defs{$1}/g;

See also ``How do I expand function calls in a string?'' in this section of the FAQ.

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[Discipulus]: oh thanks, i'm always at well as the ratchet or bucket
[Corion]: But I'm slowly starting to get into programming again - yesterday I translated my talk for YAPC::E (in Amsterdam) to English, and decided to put my Jekyll-clone to rest for the time being
[Corion]: Discipulus++ # being well is like being earnest
[marto]: hopefully next year I'll be in a position to go to Perly things in Europe :)
[Corion]: Maybe I'll use the Real Jekyll a bit to get a feel for how it actually works, and to get annoyed by it ;)
[Corion]: marto: That would be cool :) There is no kids care at Perly events unfortunately, so it's not entirely family friendly
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[marto]: Corion, not bringing the kids would make it ideal :P
[marto]: a suggestion, have one project in the list that isn't programming/perl related
[Corion]: marto: Yeah, things are more parent-friendly the way they are ;))

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