in reply to Condensing code...golfing with push and return

sub test {
    my $result = $object->createNewObject() || return;
    push @results, $result;
    return $result;
}

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More readable, too. Shorter gets less readable: 
sub test {
    push @results, $object->createNewObject() || return;
    return $results[-1];
}

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Makeshifts last the longest.

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Re: Re: Condensing code...golfing with push and return
by liz (Monsignor) on Oct 10, 2003 at 17:46 UTC
    One note:

    The original code had return undef, your code has just return. They are not the same.

    A bare return is basically equivalen to: 

    return wantarray ? () : undef;

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    your solution is equivalent to: 
    return wantarray ? (undef) : undef;

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    i.e. returns an array with a single element with an undefined value. As opposed to an empty array.

    Liz

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      Good observation, and it's good you bring it up. The point is that a list with one element evaluates as true. Most people who say return undef or return 0 actually just want to return a false value, not an explicit undef or 0. It's good habit to use an unadorned return to signal falsehood; something as innocent as 
      if( my ($obj) = test() ) {
    # ...
}

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      can trip you up.

      Makeshifts last the longest.

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        No, use the proper return type for the proper function type. If you return an empty list for false, then you'll be tripped up by something as simple as: 

        my %hash= (
    this => GetThis(),
    foo  => 'bar',
    baz  => 'biff',
);
# Which results in:
#    $hash{this} eq "foo"
#    ! exists $hash{foo}
#    $hash{bar} eq 'baz'
#    ! exists $hash{baz}
#    exists $hash{biff}

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        If your function returns lists, then an empty list is likely the correct thing to return for "false". If your function never returns lists, then I'd have it return a false scalar value not an empty list.

        BTW, my favorite false value is !1 which is a lot like '' except that it won't give a warning if used in a numeric context. (It is what Perl's own functions return for "false but not undefined".)

                        - tye
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