In my latest folly, I changed an object to use several accessor methods that would return a scalar, rather than one accessor that would return a hash ref (that had to be dereferenced and I figured was an extra hassle for any script using the module).

So, rather than getting a value like my $dir = $site->dirs()->{'uploads'};, I could write my $dir = $site->upload_dir;

All well and good, except my object also has a couple of accessor methods that should return arrays rather than scalars, so my return from the accessor method looks like:

return @{$self->{$slot}} if wantarray;
return $self->{$slot};

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It must be noted I'm using closures in a loop to create the accessor methods, hence the conditional return. See my accessor generator at the bottom.

End of preamble - this is where I got tripped up and nearly went insane - in my calling script, I wanted to join the return from the 'upload_dir' method to something else, like so:

my $dir = join '/', $site->upload_dir, $user->id;

Now, it should be obvious given my preamble that because I have called the upload_dir method in list context (because join expects a list) my method will return (or try to return) a "listified" version of my scalar upload_dir value, and hence won't be what I'm looking for - in this case, it ended up returning an empty list, and messing everything up.But it took me over an hour to figure this out (I'm not too bright at times :).

What I can't figure out is why use strict; and use warnings; didn't throw me some kind of message about trying to turn my scalar (upload_dir) into an array to return from the method?

#######################################################
# generate the generic accessor methods using closures:
for my $property (keys %properties) {
    my $slot = __PACKAGE__ . "::$property";
    no strict 'refs';    # so symbolic ref to typeglob works - see The
+ Camel p.338
    *$property = sub {
        my $self = shift;
        if (@_) {
            if ( ref $_[0] ) {    # arg is a ref, just store it
                $self->{$slot} = shift;
            }
            elsif ( $properties{$property} eq 'ARRAY' ) {    # transla
+te array to arrayref
                $self->{$slot} = [@_];
            }
            elsif ( $properties{$property} eq 'HASH' ) {    # translat
+e hash to hashref
                $self->{$slot} = {@_};
            }
            elsif ( $properties{$property} eq 'SCALAR' ) {    # scalar
+, no translation
                $self->{$slot} = shift;
            }
            else {
                die "Problem with $slot";
            }
        }
        return @{ $self->{$slot} } if wantarray;
        return $self->{$slot};
    };
}

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In reply to A vexing list vs. scalar context question. by theguvnor

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