Re: How to call a sub-routine ref

[blue_cowdawg]

in reply to How to call a sub-routine ref

alling a subroutine from a reference

assuming for a second you are talking about a reference such as

| stuff before

my $sref = \&foo 

| stuff after

then you would call it thusly:

| later

&($sref)( arg1....argn);

|

where "arg1...argn" would be replaced by the arguments you want passed to the sub.

Here is a more complete example:

#!/usr/bin/perl -w

use strict;

my $sref=\&foo;

&{$sref};

exit(0);

sub foo {
        print "This is foo.\n";
}

[greengaroo]

Yes I know. Here is another example with an anonymous subroutine:

my $ref = sub {
  print "Hello World!\n";
};

# Both are equivalent
$ref->();
&{$ref}();
# But which one is best? That is the question!

Also, I don't do simple stuff like that, I have objects and callback functions and so on. Most of the time I have deep structures that returns functions, or objects, then I want to call that function or object method.

Let me sleep on it and I will try to provide a more concrete example.

[blue_cowdawg]

Did you actually test that code?

$ cat greengaroo.pl 
use strict;

my $ref = sub {
  print "Hello World!\n";
};

# Both are equivalent
$ref->();
&{ref}();
# But which one is best? That is the question!


$ perl greengaroo.pl 
Hello World!
Undefined subroutine &main::ref called at greengaroo.pl line 9.

your second call fails.

If you fix this by rewriting it thusly:

&{$ref}();

there is still the open question of "which is better?" From a readability standpoint I'd vote for the latter rather than the former. Others may disagree but that is the essence of TIMTOWTDI. If you feel there may be a performance issue involved here have you tried profiling the code?

[greengaroo]

You are right! I forgot a $... sorry about that! Thanks for pointing it!