[tpm] Riddle me this ...

Fulko Hew fulko.hew at gmail.com
Fri Dec 28 20:28:58 PST 2012

On Fri, Dec 28, 2012 at 10:57 PM, James E Keenan <jkeen at verizon.net> wrote:

> On 12/27/12 11:43 PM, Uri Guttman wrote:
>  i want to clarify my statement there. it is the scalar prototype of not
>> that is causing this as well as its low precedence.
> I'm familiar with prototypes as an aspect of subroutines in Perl (for
> instance, Test::More::is is, under the hood, prototyped $$;$), but not with
> the concept of prototypes for operators.  Can you point me toward the
> documentation or source code for that?

Don't think about prototypes, its seems you are encountering a precedence
Check out the following, and play with variations on the theme:

 perl -e 'use Data::Dumper; sub is {print Dumper($_) foreach (@_); } is(!
1, not 1, "test1");'

$VAR1 = '';
$VAR1 = '';

what you in effect have are
arg 1:  ! 1
arg 2:  not 1, "test1"

that is, because of precedence, the latter part effectively becomes

not (1, "test1")

Then look what happens when you remove the 'not':

perl -e 'use Data::Dumper; sub is {print Dumper($_) foreach (@_); } is(! 1,
1, "test1");'
$VAR1 = '';
$VAR1 = 1;
$VAR1 = 'test1';

You see the three parameters you think your providing,
so what you really wanted is:

is ( ! 1, (not 1), "test1");

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