Re: Perl Best Practices for naming variables

[chester]

Even the distinction between $comment and $comments isn't very great, in my opinion. For reading code more than writing, that is. If using singular/plural to make the distinction like that, I'd probably make some further distinction as well, if two variable names were that similar. If all else failed maybe $a_comment (ugh, that's ugly) or $single_comment or $final_comment or $comment_about_dogs or who knows what.

So far as _ref, I guess the deciding factor is whether it's more important to easily tell references from non-references, or arrays/hashes from scalars.

If you see $var_ref, then first you can immediately tell "It's a reference!" and then you'll have determine whether it's an array ref, hash ref, or scalar ref or whatever.

On the other hand if you're using plural/singular to make the distinction, then if you see $items you first know "It's an array!", and then you're faced with figuring out (or remembering) if it's an array item or array reference. $items[1] vs. $items->[1] aren't so easy to distinguish at a glance, especially if it's buried in the middle of a bunch of other line noise.

I can easily see the argument going either way. I'd personally lean towards using _ref because I find myself mixing up hashrefs with hashes pretty often while writing code. I believe Damian mentions in the book that it's helpful if typing _ref-> as a unit becomes a habit, and it seems to work for me.

[creamygoodness]

# before Damian's book I'd have used EOREPLY
my $reply_to_chester = <<'END_REPLY_TO_CHESTER';

Exactly right, that's what Damian recommends. There's obviously someone besides him who's made it work.

I suppose I've just solved the problem he's looking to address by never using identical identifiers for different purposes. What's the advantage to me for adding those extra four characters? Now I can use %option, @option, $option, and &option in the same scope and, uh, not get them mixed up? ;) On the flip side, what's the penalty for typing$items[1] when you meant $items->[1]? No more than a missing semi-colon, or other simple syntax error. Unless your program takes a long time to compile, no big deal: run, tweak, run, tweak...

I might not find this constraint so onerous if I hadn't produced a lot of code that goes up to 78 characters.

... (time passes while Marvin peruses book) ...

It looks like the answer is, for Perl 5.8.1 onwards, the Data::Alias module. The main situation where I'd need _ref is when pulling elements out of a large and complex object for manipulation in a method. Here's what I've been doing:

sub do_stuff {
    my $self = shift;
    my $items = $self->{items};
    # Bear with me and assume I'll need $items again...
    for my $item (@$items) {
        # etc...

With the Data::Alias module, I can do this instead:

sub do_stuff {
    my $self = shift;
    alias my @items = @{ $self->{items} };
    for my $item (@items) {
        # etc...

That's probably faster. It's sure cleaner. I like. And as a bonus, now when I use _ref, it will imply something useful -- like, "this is a giant array and I want to pass it by reference".

Tasty spinach, yo,

--
Marvin Humphrey
Rectangular Research
http://www.rectangular.com

END_REPLY_TO_CHESTER