in reply to Re: Re: Avoiding user-input in sub calls.
in thread Avoiding user-input in sub calls.
&{ $functions{$doit} };
Would be seen by Perl as:
"Take the value of $functions{$doit} and treat it as a sub name"
No, there's some confusion here about references. perlman:perlref is the definitive reference (no pun intended), but I'll try to give you the short answer.
The syntax &{ SOMETHING } is, as you correctly said, a dereference. It says "Treat SOMETHING as a code reference", which means that the subroutine referred to by SOMETHING is executed. That means that SOMETHING is taken to be a reference, and in the example given, that's just what it is, as is evidenced by the code:
my %functions = ('first' => \&one, 'second' => \&two );
That \&one syntax is creating a hard reference to the subroutine one().
If, however that SOMETHING is not actually a hard reference, but is just a plain old scalar, then the "value of the scalar is taken to be the name of a variable, rather than a direct link to a (possibly) anonymous value." (from perlman:perlfref). So if the code example would have looked like this:
my %functions = ('first' => 'one', 'second' => 'two' );
... then you would be using a symbolic reference, which is what you mean by "Take the value of $functions{$doit} and treat it as a sub name". NOTE that this whole Symbolic reference business is disallowed by use strict 'refs', meaning that our friend SOMETHING must be an actual reference, and not just a name. This is probably a Good Thing.
Hope this helps. And by the way, I think the syntax $coderef->() is preferable to the equivalent &{$coderef}, since I think it just looks clearer that you're calling a subroutine...