I love Scalar::Util and List::Util. They allow me to do stuff in a cleaner, clearer, and more abstract fashion, which is what good code is all about.

Until I tried to convert the following code: 

use UNIVERSAL qw( isa );

....

my $is_blah = isa( $thing, 'Some::Class' ) && $x == 3;

...

if ( isa($value, 'HASH') || isa($value, 'ARRAY') ) {
    # Do something here
}

[download]

I tried to convert that code to the following: 

use Scalar::Util qw( blessed reftype );

...

my $is_blah = blessed( $thing ) eq 'Some::Class' && $x == 3;

...

my $r = reftype( $value );
if ( $r eq 'HASH' || $r eq 'ARRAY' ) {
    # Do something here
}

[download]

Except, that code isn't equivalent. Both reftype() and blessed() return undef, not the empty string. So, the most obvious use for reftype() and the second most obvious use for blessed() don't DWIM. Plus, ref() returns the empty string, which means they don't behave as the internal they're supposed to replace.

So, now I have to do (blessed($thing)||'') and my $r = reftype($value)||'; How annoying!

My criteria for good software:
  1. Does it work?
  2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?

In reply to Why reftype and blessed are making my life harder than it needs to be by dragonchild

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