Class::Std::Fast - faster but less secure than Class::Std
This document describes Class::Std::Fast 0.0.8
package MyClass;
use Class::Std::Fast;
1;
package main;
MyClass->new();
Class::Std::Fast allows you to use the beautiful API of Class::Std in a faster
way than Class::Std does.
You can get the object's ident via scalarifiyng your object.
Getting the objects ident is still possible via the ident method, but it's
faster to scalarify your object.
The constructor acts like Class::Std's constructor. For extended constructors
see Constructors below.
package FastObject;
use Class::Std::Fast;
1;
my $fast_obj = FastObject->new();
If you use Class::Std::Fast you shouldn't use this method. It's only existant
for downward compatibility.
# insted of
my $ident = ident $self;
# use
my $ident = ${$self};
Class::Std::Fast::initialize();
Imported from Class::Std. Please look at the documentation from Class::Std for
more details.
Class::Std::Fast exposes some of it's internals to allow the construction of
Class::Std::Fast based objects from outside the auto-generated constructors.
You should never use these methods for doing anything else. In fact you should
not use these methods at all, unless you know what you're doing.
Returns an ID for the next object to construct.
If you ever need to override the constructor created by Class::Std::Fast, be
sure to use Class::Std::Fast::ID as the source for the ID to assign to your
blessed scalar.
More precisely, you should construct your object like this:
my $self = bless \do { my $foo = Class::Std::Fast::ID } , $class;
Every other method of constructing Class::Std::Fast - based objects will lead to
data corruption (duplicate object IDs).
Returns a reference to the ID counter scalar.
The current value is the
next object ID !
You should never use this method unless you're trying to create Class::Std::Fast
objects from outside Class::Std::Fast (and possibly outside perl).
In case you do (like when creating perl objects in XS code), be sure to
post-increment the ID counter
after creating an object, which you may
do from C with
sv_inc( SvRV(id_counter_ref) )
Returns a reference to the object cache.
You should never use this method unless your're trying to (re-)create
Class::Std::Fast objects from outside Class::Std::Fast (and possibly outside
perl).
See <L/EXTENSIONS TO Class::Std> for a description of the object cache
facility.
real_can
Class::Std::Fast saves away UNIVERSAL::can as Class::Std::Fast::real_can before
overwriting it. You should not use real_can, because it does not check for
subroutines implemented via AUTOMETHOD.
It is there if you need the old
can() for speed reasons, and know what
you're doing.
Class::Std::Fast allows the user to chose between several constructor options.
- •
- Standard constructor
No special synopsis. Acts like Class::Std's constructor
- •
- Basic constructor
use Class::Std::Fast qw(2);
use Class::Std::Fast constructor => 'basic';
Does not call BUILD and START (and does not walk down the inheritance
hierarchy calling BUILD and START).
Does not perform any attribute initializations.
Really fast, but very basic.
- •
- No constructor
use Class::Std::Fast qw(3);
use Class::Std::Fast constructor => 'none';
No constructor is exported into the calling class.
The recommended usage is:
use Class::Std::Fast constructor => none;
sub new {
my $self = bless \do { my $foo = Class::Std::Fast::ID } , $_[0];
# do what you need to do after that
}
If you use the Object Cache (see below) the recommended usage is:
use Class::Std::Fast constructor => 'none', cache => 1;
sub new {
my $self = pop @{ Class::Std::Fast::OBJECT_CACHE_REF()->{ $_[0] } }
|| bless \do { my $foo = Class::Std::Fast::ID() } , $_[0];
}
Class::Std sorts the @ISA hierarchy before traversing it to avoid cleaning up
the wrong class first. However, this is unneccessary if the class in question
has a linear inheritance tree.
Class authors may disable sorting by calling
use Class::Std::Fast unsorted => 1;
Use only if you know your class' complete inheritance tree...
Synopsis
use Class::Std::Fast cache => 1;
Description
While inside out objects are basically an implementation of the Flyweight
Pattern (object data is stored outside the object), there's still one aspect
missing: object reuse. While Class::Std::Fast does not provide flyweights in
the classical sense (one object re-used again and again), it provides
something close to it: An object cache for re-using destroyed objects.
The object cache is implemented as a simple hash with the class names of the
cached objects as keys, and a list ref of cached objects as values.
The object cache is filled by the DESTROY method exported into all
Class::Std::Fast based objects: Instead of actually destroying the blessed
scalar reference (Class::Std::Fast based objects are nothing more), the object
to be destroyed is pushed into it's class' object cache.
new() in turn does not need to create a new blessed scalar, but can just
pop one off the object cache (which is a magnitude faster).
Using the object cache is recommended for persistent applications (like running
under mod_perl), or applications creating and destroying lots of
Class::Std::Fast based objects again and again.
The exported constructor automatically uses the Object Cache when caching is
enabled by setting the cache import flag to a true value.
For an example of a user-defined constructor see "Constructors" above.
Memory overhead
The object cache trades speed for memory. This is a very perlish way for
adressing performance issues, but may cause your application to blow up if
you're short of memory.
On a 32bit Linux, Devel::Size reports 44 bytes for a Class::Std::Fast based
object - so a cache containing 1 000 000 (one million) of objects needs around
50MB of memory (Devel Size only reports the memory use it can see - the actual
usage is system dependent and something between 4 and 32 bytes more).
If you are anxious about falling short of memory, only enable caching for those
classes whose objects you know to be frequently created and destroyed, and
leave it turned off for the less frequently used classes - this gives you both
speed benefits, and avoids holding a cache of object that will never be needed
again.
see Class::Std.
Additional diagnostics are:
- •
- Class::Std::Fast loaded too late - put >use
Class::Std::Fast< somewhere at the top of your application (warning)
Class::Std has been "use"d before Class::Std::Fast. While both
classes happily coexist in one application, Class::Std::Fast must be
loaded first for maximum speedup.
This is due to both classes overwriting UNIVERSAL::can. Class::Std::Fast
uses the original (fast) can where appropritate, but cannot access it if
Class::Std has overwritten it before with it's (slow) replacement.
- •
- version
- •
- Class::Std
- •
- Carp
see Class::Std
- •
- You can't use the :SCALARIFY attribute for your Objects.
We use an increment for building identifiers and not Scalar::Util::refaddr
like Class::Std.
- •
- Inheriting from non-Class::Std::Fast modules does not work
You cannot inherit from non-Class::Std::Fast classes, not even if you
overwrite the default constructor. To be more precise, you cannot inherit
from classes which use something different from numeric blessed scalar
references as their objects. Even so inheriting from similarly contructed
classes like Object::InsideOut could work, you would have to make sure
that object IDs cannot be duplicated. It is therefore strongly discouraged
to build classes with Class::Std::Fast derived from non-Class::Std::Fast
classes.
If you really need to inherit from non-Class::Std::Fast modules, make sure
you use Class::Std::Fast::ID as described above for creating objects.
- •
- No runtime initialization with constructor => 'basic' /
'none'
When eval'ing Class::Std::Fast based classes using the basic constructor,
make sure the last line is
Class::Std::Fast::initialize();
In contrast to Class::Std, Class::Std::Fast performs no run-time
initialization when the basic constructor is enabled, so your code has to
do it itself.
The same holds true for constructor => 'none', of course.
CUMULATIVE, PRIVATE, RESTRICTED and anticumulative methods won't work if you
leave out this line.
- Last changed by
- $Author: ac0v $
- Id
- $Id: Fast.pm 469 2008-05-26 11:26:35Z ac0v $
- Revision
- $Revision: 469 $
- Date
- $Date: 2008-05-26 13:26:35 +0200 (Mon, 26 May 2008) $
- HeadURL
- $HeadURL:
file:///var/svn/repos/Hyper/Class-Std-Fast/branches/0.0.8/lib/Class/Std/Fast.pm
$
Andreas 'ac0v' Specht "<
[email protected]>"
Martin Kutter "<
[email protected]>"
Copyright (c) 2007, Andreas Specht "<
[email protected]>". All rights
reserved.
This module is free software; you can redistribute it and/or modify it under the
same terms as Perl itself.