in reply to Format / Logical Expression / Style Opinions: my, ternary, subroutine, @_

I no longer fear the ternary operator, so this is readable enough. There must be a clearer way to express the logic, though. Having the first parameter be undefined when @_ isn't quite long enough, and croaking if @_ isn't exactly the right length ... it makes my brain hurt a little.

What about switching around the order of the parameters?

sub xyz {
    my ($xxx, $yyy, $ttt) = @_;

    # You could also say -> if( !$xxx || !$yyy )
    # if you wanted to avoid 'unless' like the PBB says
    unless ($xxx && $yyy) {
        croak('Not good.');
    }

    # ...
}

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This way we don't have to enforce a specific size for @_, too. Double bonus.

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Re^2: Format Style Opinions: my, ternary, subroutine
by jffry (Hermit) on Dec 04, 2007 at 18:28 UTC

    Wow. That is a simpler way to express it. Thanks. I think I'm still in that "everything is a nail" phase with the ternary op.

    However, I don't think it is wise to quietly keep going if a 4th argument is passed to it. I don't know about anyone else who might use this sub, but I certainly want to tell myself if I'm using it wrong.

[reply]

      I understand your nervousness about extra arguments, but I've learned that they don't really matter in Perl. An analogy that comes to mind is filling a glass of water. If I hand you a cup and you pour a gallon of water into it, all I get back is a cup. I might make fun of you for being so sloppy, but who cares? After all, I have the cup of water that I wanted.

      Still, if it is important to you, you can enforce it with logic in your sub.

      sub xyz {
    my $xxx = shift || croak('Missing xxx parameter');
    my $yyy = shift || croak('Missing yyy parameter');
    my $ttt = shift;

    # Enforce length of function parameter list.
    if (@_) {
        croak('Too many args for xyz!');
    }

    # ...
}

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      ... but things like that risk making the code a little harder to read.

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