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Re: Closure Explanation

by Anonymous Monk
on Apr 30, 2010 at 18:35 UTC ( #837832=note: print w/ replies, xml ) Need Help??


in reply to Closure Explanation

Is callback the same as closure in Perl?


Comment on Re: Closure Explanation
Re^2: Closure Explanation
by TGI (Vicar) 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

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

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
    Callback example:
    sub exec_callback { my $f = shift; $f->(); } exec_callback(sub {print "hello\n"});
    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.

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