Re: Use reference for functions in functions

[AnomalousMonk]

sub func1 (\$)
{ my $object=shift;
  $object->doSomething;
}

In addition to the problems pointed out by BrowserUk and 7stud, the code quoted above from the OP includes another practice you'll probably want to drop at the earliest opportunity: using prototypes. (See Far More than Everything You've Ever Wanted to Know about Prototypes in Perl -- by Tom Christiansen for a thorough discussion of many good reasons to avoid them unless you really know what they're doing.)

The  (\$) prototype in the quoted code causes a reference to a scalar to be passed to the function as an argument. This scalar was an object reference to begin with, so what you wind up with is a reference-to-a-reference. This reference-to-a-reference must then be de-referenced in order to use it to invoke a class method. E.g.,
    ${$object}->doSomething;
in the quoted code (assuming an otherwise-normal OO idiom). This is akin to putting your pants on over your head: it's a neat party trick, but probably not something you want to do every morning.

>perl -wMstrict -le
"package Dog;
 ;;
 use List::Util qw(sum);
 ;;
 sub new {
   my $class = shift;
   my $self = {};
   bless $self, $class;
   }
 ;;
 sub bark { printf 'woof '; }
 ;;
 sub do_math { my $self = shift;  $self->bark for 1 .. sum @_; }
 ;;
 ;;
 package main;
 ;;
 sub func1 (\$) {
   my $obj = shift;
   ${$obj}->bark();
   print qq{\n};
   }
 ;;
 sub func2 (\$;@) {
   my $obj = shift;
   ${$obj}->do_math(@_);
   print qq{\n};
   }
 ;;
 my $dog = Dog->new();
 func1($dog);
 func2($dog, 3, 2, 1);
"
woof

woof woof woof woof woof woof