If you're developing a complex application, you'll probably want to
split it in a horde of specialized modules. Few things to remember:
==
You will probably feel the need to use static variables (i.e. variables
shared with all instances of a given class) at some point. For example
if you have a singleton object you might have something like that:
package Your::Singleton;
use strict;
use 5.6;
use our $ETERNAL = undef;
sub instance
{
my $class = shift;
return $ETERNAL if (defined $ETERNAL);
$ETERNAL = $class->new (@_);
return $ETERNAL;
}
sub new { ... blah blah code ... }
1;
ALWAYS reinitialize $Your::Singleton::ETERNAL on each query!
mod_perl will *NOT* do it for you.
You might think 'ah yeah but it would be nice if
$Your::Singleton::ETERNAL could be persistent across queries...' which
is sometimes desirable, but remember that if you have multiple instances
of your application running on the same apache,
$Your::Singleton::ETERNAL will be common to ALL of them.
==
Cyclic memory references are dangerous, try to avoid them as much as
possible! Perl garbage collector does miserably fails in the case of
cyclic refs.
If you have a cycling references that keep going out of scope, they will
never be garbage collected and your server might have some trouble :-)
==
Beware of regular expressions /o modifier! The application I'm working
on has a cool feature heavily using regular expressions: automagic
hyperlinking of text / html data when appropriate. I used to use the /o
modifier and got a few nasty surprises (until I discovered the mod_perl
guide traps page)
==
Other than that, more generally speaking:
Always hide classes implementation with method calls! Not so long ago I
did tend to write using less method calls and directly accessing
object's attributes and now this is my #1 source of maintenance problem
and headaches.
It you think it's too slow then consider it's better to buy a bigger CPU
than 3 tons of aspirin. Also avoid using packages names inside functions
as much as possible, as it tends to screw inheritance.
Finally my biggest piece of advice:
ENFORCE a coding style. ENFORCE using english for variable, function
names and comments (for example although I'm French I really can't stand
code written with french variable names and comments! The Perl language
is using English keywords after all. Be consistent FFS) . ENFORCE
commenting what every single method does.
Having said that I do naturally tend to write awful code that only I can
understand, but at least everything is properly commented :)
Cheers,
--
IT'S TIME FOR A DIFFERENT KIND OF WEB
================================================================
Jean-Michel Hiver - Software Director
[EMAIL PROTECTED]
+44 (0)114 221 4968
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