http://www.perlmonks.org?node_id=1004998


in reply to grep {CONSTANT} @list

Nothing to do with grep in particular, or constants.

use constant REGEXP => qr(a);
print grep { REGEXP } qw(a b c);

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... is equivalent to:

my @tmp;
foreach (qw(a b c)) {
   push @tmp, $_ if qr(a);
}
print @tmp;

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See the problem now? if qr(a) is always true. if qr(anything) is always true.

Try:

print grep { $_ =~ REGEXP } @list;

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perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

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