Sorry to the original thread as we are now a bit off the beaten topic.

Yes. It is a method. It will skip $code's ->isa. It breaks overloading. It also works in 99% of the use cases (probably more) that the general programming population will use and in those cases where somebody has created an object that pretends to be code they can simply pass sub { &$code } and suddenly it works fine. Changing to $code->isa('CODE') in this case would actually break 99% of use cases because it only allows for objects that are CODE (not bare coderefs). I think it is wonderful that Perl 5 (and other languages) can call methods in a more functional form if the need arises.

Using defined &$code almost works but it breaks if a non-coderef reference is passed in. It also doesn't go the full route of supporting overloaded objects so it isn't any more of a solution.
The only thing that "might" be able to handle 100% of cases is something like

use Scalar::Util qw(blessed);
my $is_code = blessed($code) ? $code->can('&{}') : ref($code) eq 'CODE
+';
[download]

UPDATE: - Yup - I missed blessed coderefs which would have to be checked for with eval { defined &$code }. The corrected code might look like

my $is_code = ! blessed($code)
            ? ref($code) eq 'CODE'
            : $code->can('&{}')
              || $code->isa('CODE') # arguably not a good test (bless 
+{}, 'CODE')
              || eval { defined &$code }; # arguably bad because it ge
+ts called in some contexts
[download]

Arguably that isn't all that bad. I'm sure there is probably still a case I'm missing. I do know of a few companies that are still pre-Perl 5.8 and the Scalar::Util::blessed route isn't even an option for them.

Yes. I agree that things can break. Perl 5 has problems in being able to type data or easily (s/easily/succinctly/) detect the type or capabilities of data. There are many things that can break during argument passing in Perl 5. There are basic things that can be done to check for basic types of data. If advanced users want to pass in advanced types, the basic checks won't prohibit them - they just force them to wrap them in more palatable forms. Although many times the "basic" checks I've seen are indeed poorly done and restrict viable options that would otherwise work just fine.

I've probably already gone too far. There are many who feel very strongly about this issue. But the picture painted is usually more severe that is necessary and when presented as a blanket statement hides useful, working use cases.

Often on Perlmonks there is the assumption that one doesn't know what they are doing when they actually do. And of course there are those that assume they know what they are doing when they actually do not.

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