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Postings from August 2012
On Fri, Aug 17, 2012 at 8:20 AM, Ed Avis <eda@waniasset.com> wrote:
>
> Good point. I was assuming that there is a concept of scalar equality defined
> by the language and accessible to the programmer directly. But this is not the
Perl gives you numeric and string equality (and allows overriding of
each). Consider this:
use v5.10;
use strict;
use warnings;
use bignum;
use Scalar::Util qw/refaddr/;
my $x = 42;
my $y = 42;
say '$x is object at ' . refaddr($x);
say '$y is object at ' . refaddr($y);
# output:
# $x is object at 40813776
# $y is object at 40814952
If you tested C<< $x in ( $y ) >>, is that true or false? $x and $y
are different objects, yet the compare true numerically. Is $x in the
list or not?
Thus your conception of "in" is visually elegant -- and I like that --
but just isn't specific enough for the dynamic nature of Perl, whereas
junctions force the programmer to clarify what comparison they
actually want for a membership test.
C<< $x == any( $y ) >>
C<< refaddr($x) == any( map { refaddr $_ } $y ) >>
-- David
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