Friday, July 30, 2004

Sufficiently Advanced Technologies

You have to wonder how Damian Conway makes it through OSCON, he spent the first two days giving tutorials, and he's talked several times a day during the conference proper. However a Conway talk is always interesting, you normally spend it either sitting in awe of his achievement, his presentation style or just his raw energy, if you aren't frantically trying to write down every word he says...

Damian starting talking about Perl magic, for instance

package MyClass

use Sub::CallAsMethod;

sub foo
my $self = shift;
bar(); # rather than $self->bar();

The interface to Sub::CallAsMethod is as minial as possible, non-existant in fact, the module's effect is as indistinguishable from magic.

The existance of these sorts of modules isn't new, it's been around for some time. The main problem with them is use strict which normally breaks, although of course use diagnostics is worse "not only are you executed for your sins, you're given a long lecture about it first".

A good example of a magical module is IO::All which is definately sufficiently advanced, it's magic, but given a sufficently easy mind there isn't any technology that can't be pushed too far. Damian has extended IO::All to do this,

use IO::All::Pulp::Fiction;

my @array = <~/file.txt>;

Also Perl6::Say which will add the newline automatically to print statements so long as $/ isn't definied. If you want to find sufficiently advanced technology, look in the Perl6 namespace.

Sufficently advanced technology doesn't have to appear our of thin air, find the bits of your code that annoy you, and then auto-magically hide them so you'll never have to do it again. For instance look at Damian's IO::Prompt module

use IO::Prompt;

while( prompt "next: " ) {
print "Ypu said 'S_'\n";

Also, comments, comments are passive and boring. they don't really pull their weight. So Damian decided that comments should be interactive and useful, last year he demo'ed a module IO::Progress to construct progress bars, but he hasn't used it, it wasn't sufficiently advanced. The interface wasn't magical enough. So he wote Smart::Comments. Here you comment each initialisation step with a picture of what you'd like printed out to the progress bar (while loops even have exponential slow downs). Smart::Comments uses source filtering since tehre aren't any hooks in Perl 5 to interogate the comments.

use Smart::Comments;

for my $i ( 1..10) { ### Looping... done

The module can also do things like,

###check: $i == 10;

they aren't smart comments unless they're smart.

Then he started talking about his new version of Lingua::Inflect which has so much magic I can't even fit the explanation in the space provided.

Perl's stringths are that it does the heavy lifting for you. Damian argues that you should make that the strength of your own modules, we should think about what we can remove from the interface of our modules to make them simpler to use, almost magic infact.