[Israel.pm] Useless use of eq

[Gabor Szabo]

On Thu, May 29, 2008 at 11:55 PM, Shmuel Fomberg <semuelf at 012.net.il> wrote:
> Hi All.
>
> Can anyone tell me why this line is OK:
> ok( ( $hash->{a} == 7 ) && ( $hash->{b} == 256 ) ,
> "Struct: Build: correct elements");
>
> While this line:
> ok( ( $hash->{a} == 7 ) and ( $hash->{b} == 256 ) ,
> "Struct: Build: correct elements");
> cause a warning:
> Useless use of numeric eq (==) in void context
> ?


gabor at notebook:~$ perl -MO=Deparse a.pl
use warnings;
ok($$hash{'a'} == 7 && $$hash{'b'} == 256, 'Struct: Build: correct elements');
ok($$hash{'a'} == 7 && ($$hash{'b'} == 256, 'Struct: Build: correct elements'));

Or in words:

&& has higher precedence than the comma after the condition while
'and' has lower precedence.

Then the      $$hash{'b'} == 256    has no consequence so it is "useless".

Gabor

-- 
Gabor Szabo http://szabgab.com/blog.html
Perl Training in Israel http://www.pti.co.il/
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