I tend to use warn (and its relatives from Carp) in production code - debugging by printing to STDERR since, as has been pointed out elsewhere on this thread, warnings are trappable - indeed, my test harnesses (using Test::More), attempt to to verify that the code is/isn't doing something unexpected by catching warnings using... 
my $WARN;
local $SIG{__WARN__} = sub { $WARN = "@_" };
.
.
my $WARN = '';
some_op();
like($WARN, '/^$/', 'some_op() - no warnings');

[download]

Update:

Added example call - for clarity.

A user level that continues to overstate my experience :-))

In reply to Re: using warn instead or print STDERR? by Bloodnok
in thread using warn instead or print STDERR? by leocharre

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