How to call a sub from a variable with the name of the sub?

Question

Given the following code:

sub foo {
    say 'Hello';
}
my $call_me = 'foo';

How do I call the sub foo using $call_me?

Sunil

Answer 1

Use:

::( "&" ~ $call_me )()

:: accesses the symbol table in the current package; subs are stored in that symbol table with the sigil & which is why we have to concatenate (~) the name with that to go from string to the function; that symbol table maps identifiers to the actual function.

For methods, this is easier:

my $method-name = "foo";
$object."$method-name"();

Note that you can create a name inside the "" there, it doesn't have to be just a variable name.

Also note that the () are required in that case.

Flinty

Thank you, especially for the explanation! – Sunil

You'll have to thank @elizabeth-mattijsen too :-) – Flinty

Great answer! I just note a couple of variations (i) my $c = '&foo'; ::(~$c)() embed the & in the name and uses str concat (~) as prefix to coerce $c to Str or (ii) my $d = 'foo''; ::("&$d")() use double quotes to interpolate the (&) onto the front. – Crooks

You should use &::($name) instead of ::("&" ~ $name) – Mingo

@Mingo any reason? Is it just more idiomatic? – Flinty

@Flinty it will at least save on a string-concat (creating a new short-lived temporary string) etc... – Interplead