http://www.perlmonks.org?node_id=837832


in reply to Closure Explanation

Is callback the same as closure in Perl?

Replies are listed 'Best First'.
Re^2: Closure Explanation
by runrig (Abbot) on Apr 30, 2010 at 20:37 UTC
    Closure example:
    
sub rtn_closure {
  my $i = shift;
  return sub { $i++ };
}

# f's i starts at 5
my $f = rtn_closure(5);
print $f->(),"\n";  # Prints 5
print $f->(), "\n"; # Prints 6

# g gets a separate i that starts at 10
my $g = rtn_closure(10);
print $g->(), "\n"; # Prints 10
print $g->(), "\n"; # Prints 11
print $f->(), "\n"; # Prints 7

    [download]
    Callback example:
    
sub exec_callback {
  my $f = shift;
  $f->();
}

exec_callback(sub {print "hello\n"});

    [download]
    Does that help? A callback does not have to close over any variables, although it could. A closure occurs whenever a function refers to a variable in an outer scope.
[reply]
[d/l]
[select]
Re^2: Closure Explanation
by TGI (Parson) on Apr 30, 2010 at 19:06 UTC

    No, a callback need not be closed over any variables. A closure may be called by any means a normal function is.


    TGI says moo

[reply]
      Do you have a sample code showing the difference between the two?

[reply]

In Section Seekers of Perl Wisdom