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Very API

June 25, 2010
tags: , ,

In my last post about extending autobox::Core, I touched on API choices. So let me expand on this a little bit here and in some more in posts to come.

In all bar one of my autobox examples I used $_[0] to pass the iterator object. For eg:

['a'..'z']->iterate( sub{
    print $_[0]->currentIndex, ' => ', $_[0]->current;
});

But in the last code example I went for $_[0] having the value and $_[1] the iterator object:

['a'..'z']->iterate( sub{
    print $_[1]->currentIndex, ' => ', $_[0];
});

And to help avoid getting cross-eyed with $_[] then this is nicer on the eye if a tad longer:

['a'..'z']->iterate( sub{
	my ($v, $iter) = @_;
    print $iter->currentIndex, ' => ', $v;
});

But hold on, is there a preference to which way round these should be assigned to @_? Would it be better other way round because value can be got at from the iterator object anyway? (one shift and away!)

So perhaps using $_ is best?

['a'..'z']->iterate( sub{
    print $_->currentIndex, ' => ', $_->current;
});

I like this a lot. But it would be amiss not to take advantage of using $_ for the value and $_[0] for iterator so that we can write code like this:

['a'..'z']->iterate( sub{
	print $_[0]->getNext if m/[aeiou]/;
});

However note the print $_[0]->getNext and not just plain print :(

I don’t think there is a canonical answer to this but my preference is to use $_ has the iterator object… but with probably value & the iterator (again!) passed through @_ (ie. the kitchen sink approach!).

sub autobox::Core::ARRAY::iterate {
    my ($array, $code) = @_;
    my $iter = Array::Iterator->new( $array );
    
    while ($iter->hasNext) {
        local $_ = $iter;
        $code->( $iter->getNext, $iter );
    }

    return wantarray ? @$array : $array;
}

Note the return wantarray ? @$array : $array; addition. This keeps the autobox chaining going and is good adherence to autobox API (though in this iterator context it probably isn’t of much benefit).

/I3az/

PS. Let me just add “Perl” here because despite lots of perl code snippets I haven’t mentioned Perl, CPAN or Ironman at all and I’m still wary whether ironman will pick up the perl tag.

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One Comment leave one →
  1. August 1, 2010 8:55 am

    I would like to exchange links with your site transfixedbutnotdead.com
    Is this possible?

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