How to detect a returns value gracefully

RatKing has asked for the wisdom of the Perl Monks concerning the following question:

Dear monks,

I have the following code:

my $result = my_function();
if ( ref $result eq 'SCALAR' ) {
 # Handle scalar return value
} elsif ( ref $result eq 'ARRAY' ) {
 # Handle Array return value
}
[download]

Which works quite well till I have my_function return not a scalar or an array but a reference to one of these two options. At that point ref $result will always tell me I am looking at an reference which is of course correct but not very handy for me to handle the output in different ways. So my question is how to detect what my reference is refering to is it a scalar or an array?

Comment on How to detect a returns value gracefully Download Code

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Re: How to detect a returns value gracefully by citromatik (Curate) on Feb 26, 2009 at 11:00 UTC
IMHO, a function that can return an array, a scalar, a reference to an array or a reference to a scalar is probably not well designed and is a candidate to be reformulated BTW, the code you posted could be better written using wantarray inside the function `sub my_fun { # blah, blah, return wantarray ? @array : $scalar; }` [download] Hope this helps citromatik	[reply] [d/l]
Re: How to detect a returns value gracefully by ELISHEVA (Prior) on Feb 26, 2009 at 08:31 UTC
Check `ref $$result` instead of `$result` whenever `ref($result) eq 'REF'`. `use strict; use warnings; my $aFoo = []; my $result = \$aFoo; print 'ref $result : ' . ref($result) . "\n"; print 'ref $$result : ' . ref($$result) . "\n";` [download] prints `ref $result : REF ref $$result : ARRAY` [download] Best, beth	[reply] [d/l] [select]
Re^2: How to detect a returns value gracefully by Anonymous Monk on Feb 26, 2009 at 08:39 UTC
You shouldn't use references until you've read perlref	[reply]
Re^3: How to detect a returns value gracefully by almut (Canon) on Feb 26, 2009 at 11:18 UTC
Care to explain what the issue is instead of spreading FUD?	[reply]
Re^4: How to detect a returns value gracefully by Anonymous Monk on Feb 26, 2009 at 19:53 UTC
Re^5: How to detect a returns value gracefully by almut (Canon) on Feb 26, 2009 at 20:00 UTC
Some notes below your chosen depth have not been shown here
Re: How to detect a returns value gracefully by Joost (Canon) on Feb 26, 2009 at 11:43 UTC
The code you posted doesn't work like you described. There is no way to test if a function returns a list or not, since capturing the return value(s) forces the function to return either a list (which isn't an array) or a scalar. This is by design and you cannot work around it. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply]
Re: How to detect a returns value gracefully by Fletch (Bishop) on Feb 26, 2009 at 13:42 UTC
There's also the Damian module Contextual::Return which lets you return a magical value that behaves differently when used as different types of values (and yes, it's OK for general use). The cake is a lie. The cake is a lie. The cake is a lie.	[reply]