Sometimes I wonder if a bit uncommon syntax is valid, and if it is, if anyone actually uses it. For example, I don't see "my" on the right side of an assignment operator very often:
my $a = my $b;
I've started using Google Code Search to turn up prior art.
In this case, I quickly discovered that, Yes, that's valid, and people are actually using it.
Remember to include lang:perl to restrict a search to Perl.
Hmm, usually for searches like this I prefer krugle.org over Google, but in this case Google wins by a very wide margin. Krugle can't even find one instance of that syntax.
