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

Hey all! i was wondering how to filter out variables from a multiline string.. example: 
tttt $x=123 ttt @c=qw/1 2 3/;
tt $xxx ttttt @something

[download]
so the output would be: $x @c $xxx. thanks guys

Replies are listed 'Best First'.
Re: regex help
by JavaFan (Canon) on Apr 21, 2012 at 20:47 UTC
    Questions:
    • What's the criteria that makes that @something isn't part of the output?
    • What ought to be the output when variables like $array[1], @hash{"foo", "bar"}, qq[foo${bar}baz], @{$ref}{1, 2}, ${__PACKAGE__ . '::foo'}, etc are being used?
[reply]
[d/l]
[select]
      no criteria, just missed it out by accident. all i need to do is extract variable,array names. variables like $array1 should just be $array. i guess i will need to avoid ${__PACKAGE__
[reply]
        Perhaps then all what you need is (untested): 
        /(?(DEFINE)
   (?<sigil>       [\$\@%&*])
   (?<name_atom>   (?: [_A-Za-z][_A-Za-z0-9]* | [0-9]+) )
   (?<separator>   (?: :: | '))
   (?<name>        (?: (?&separator)? (?&name_atom) 
                    (?:(?&separator)  (?&name_atom))*))
   (?<punct>       \S))
 (?&sigil) \s* (?:(?&name) | (?&punct))
/x

        [download]
[reply]
[d/l]
Re: regex help
by NetWallah (Canon) on Apr 21, 2012 at 21:19 UTC
    Make sure the code you are running throught he regex is not interpolated. 
    perl -e 'print qq|$_\n| for q|tttt $x=123 ttt @c=qw/1 2 3/; tt $xxx tt
+ttt @something|=~/([\$\@\%]\w+)/g'
$x
@c
$xxx
@something

    [download]
    Update:This code is simplistic. JavaFan's regex (++), above, is much more rigorous.

                 All great truths begin as blasphemies.
                       ― George Bernard Shaw, writer, Nobel laureate (1856-1950)

[reply]
[d/l]

Back to Seekers of Perl Wisdom