Re^2: How to call a sub-routine ref

[greengaroo]

Imagine this:

&{$hashref->{'key'}}('key');

vs.

$hashref->{'key'}->('key');

Don't you think the second could lead to confusions?

I'm just trying to find what is best, I honestly prefer the first but I've never seen it until recently, so I am thinking maybe no one uses it because it may be harder to understand at first sight.

[roboticus]

greengaroo:

Odd, I find your examples a good case for using the second one. Again, different people will find different things more clear.

When I use hashes, I generally use $$h{foo} in preference to $h->{foo}, primarily because it's easier to type, and I use hashes quite a bit. If I were trying to make it visually distinctive, I'd make the harder to type one be for the less frequently used case. Thus, I'd use something like:

$$hashref{key}->('arg');

To my eye, that stands out better. (But with my luck, it would blow up, so I'd better whip up a test...)

$ cat t.pl
use strict;
use warnings;

sub p { print "foo(", join(", ", @_), ")\n"; }

my $hr = { key=>\&p };

$$hr{key}->('arg');

$ perl t.pl
foo(arg)

...roboticus

When your only tool is a hammer, all problems look like your thumb.

[BillKSmith]

I like the second rule in perlref.

Anywhere you'd put an identifier (or chain of identifiers) as part of a variable or subroutine name, you can replace the identifier with a BLOCK returning a reference of the correct type.

Sure, the result is often ugly, but there are no exceptions or special cases. What more could my poor memory want.

[BrowserUk]

For that particular case, you don't need either the -> or the &{}:

sub x{ say "x got [ @_ ]"; };;

$h{x} = \&x;;

$href = \%h;;

$href->{x}('fred','bill');;
x got [ fred bill ]

[ikegami]

I find the first one much harder to read. The difference between ( and { is subtle, but properly named variables ($handlers->{$event_name}->($event)) would make that irrelevant.