Conrad (>):
> Is there something more up-to-date concerning "Perl 6 best practices" that
> are presently-recommended (by p6l or @Larry) than the following item on the
> Perl 6 wiki?
If you ask me, "best practices" evolve as a countering force to enough
people using less-than-ideal practices to create maintenance headaches
or suboptimal solutions noticeable enough for someone to put together
a collection of tips and insights.
I use Perl 6 every day. My problem is not that I encounter badly
thought-out Perl 6 code frequently -- it's that we're targeting
incomplete Perl 6 implementations and have to go against what would
ordinarily be seen as best practices in order to circumvent bugs and
missing features in various layers of the Perl 6 implementation stack.
The tricks we evolve to do this are far removed from best practices:
they are closer to the worst advice you could give a Perl 6 beginner.
(Because most of them solve a problem _without_ the help of some
convenient Perl 6 feature.)
That said, I do have one Perl 6-specific "best practice". I know
you're looking for a collection, but one's a start. :) Here it is:
Do not combine 'ne' and '|', like this:
die "Unrecognized directive: TMPL_$directive"
if $directive ne 'VAR' | 'LOOP' | 'IF';
One is tempted to assume that this means the same as "$directive ne
'VAR' || $directive ne 'LOOP' || $directive ne 'IF"", but it doesn't.
Instead, it's a negated string comparison against three values, the
results of which are then OR-ed together. The condition will always be
true, because there's always at least two values that $directive is
not string-equal to.
The "correct" form using junctions would be this:
die "Unrecognized directive: TMPL_$directive"
if $directive ne 'VAR' & 'LOOP' & 'IF';
But my brain refuses to let me believe that this is what I want to
write. ("If $directive is not string-equal to 'VAR' and 'LOOP' and
'IF'... well of course it isn't!")
So instead, I'd use "eq", and negate the whole expression:
die "Unrecognized directive: TMPL_$directive"
if !($directive eq 'VAR' | 'LOOP' | 'IF');
The more general advice, then, would be not to use junctions together
with negated equality operators. Instead, use the non-negated equality
operator, and negate the whole expression.
// Carl
