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Re^6: Using grep and glob to find directories containing file

by muba (Priest)
on Feb 04, 2013 at 02:52 UTC ( #1016889=note: print w/ replies, xml ) Need Help??


in reply to Re^5: Using grep and glob to find directories containing file
in thread Using grep and glob to find directories containing file

That's not a list, that's the comma operator in scalar context, which will disregard its left hand value and return its right hand value.

So in my $x = ('a', 'b', 'c');, 'a' and 'b' get discarded, and 'c' gets assigned to $x, as your snippet proves. This behaviour is documented (see the link I gave) and also demonstrated by B::Deparse:

$ perl -MO=Deparse -E '$x = ("a", "b", "c");' use feature 'current_sub', 'evalbytes', 'fc', 'say', 'state', 'switch' +, 'unicode_strings', 'unicode_eval'; $x = ('???', '???', 'c'); -e syntax OK

However, =()= is an idiomatic way to enforce list context. The details are better explained in Perl Idioms Explained - my $count = () = /.../g than I could do it myself, but just to demonstrate that it works, consider the following.

$ perl -MO=Deparse -E '$x =()= ("a", "b", "c"); print $x' use feature 'current_sub', 'evalbytes', 'fc', 'say', 'state', 'switch' +, 'unicode_strings', 'unicode_eval'; $x = () = ('a', 'b', 'c'); print $x; -e syntax OK $ perl -E '$x =()= ("a", "b", "c"); print $x' 3


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