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Re^3: Hope a subroutine will return undef by default

by LanX (Canon)
on Feb 11, 2014 at 23:04 UTC ( #1074533=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Hope a subroutine will return undef by default
in thread Hope a subroutine will return undef by default

well if you really wanna "golf" better skip the semicolon and safe 33% of the necessary characters. ;-)

Cheers Rolf

( addicted to the Perl Programming Language)


Comment on Re^3: Hope a subroutine will return undef by default
Re^4: Hope a subroutine will return undef by default
by tobyink (Abbot) on Feb 11, 2014 at 23:47 UTC

    My main concern is not one of brevity. The return keyword does two things: it establishes the return value of the function, and it also acts as flow-control, exiting the current function.

    (); is a way to set the return value of a function to nothing without using a keyword that screams out "flow-control" to readers skimming the code.

    Update: As an aside, in Kavorka there is a lot of Perl code re-writing that goes on. For example, writing something like this:

    method foo ($x) { return $x + 1; }

    Will actually be rewritten internally to something like:

    sub foo { my $self = shift; my $x = @_>=1 ? shift(@_) : croak("Requires \$x"); return $x + 1; }

    So far, so good. But what about this method:

    method bar ($x) { }

    We'd expect it to return nothing. But it's rewritten to something like:

    sub bar { my $self = shift; my $x = @_>=1 ? shift(@_) : croak("Requires \$x"); }

    Which would actually return $x! The solution? Kavorka inserts (); into the sub body after unpacking parameters from @_. It couldn't use return because that's flow-control, and would prevent the main body of the function from executing.

    use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name
      IMHO its still flow control (its an exit point), so no need to hide it.

      (); is fine for short lambdas, otherwise IMHO explicit is better than implicit.

      YMMV! :)

      Cheers Rolf

      ( addicted to the Perl Programming Language)

Re^4: Hope a subroutine will return undef by default
by choroba (Abbot) on Feb 11, 2014 at 23:56 UTC
    It is a good habit to omit semicolons after the commands that should not be followed by anything else (return, next, etc.). If you accidentaly add something, you get an error.
    لսႽ ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

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