package FOOBAR;
use Exporter;
use AutoLoader;
@ISA = qw(Exporter AutoLoader);
__END__
prior to the actual subroutine declarations. All code that is before the
marker will be loaded and compiled when the module is used. At the marker,
perl will cease reading and parsing. See also the AutoSplit module, a utility that automatically splits a module into a collection of
files for autoloading.
When a subroutine not yet in memory is called, the AUTOLOAD function attempts to locate it in a directory relative to the location of
the module file itself. As an example, assume POSIX.pm is located in
/usr/local/lib/perl5/POSIX.pm. The autoloader will look for perl subroutines for this package in /usr/local/lib/perl5/auto/POSIX/*.al. The .al file is named using the subroutine name, sans package.
import method that will load the
stubs (from autosplit.ix file) of the calling module. These stubs are needed to make inheritance
work correctly for class modules.
Modules that inherit from AutoLoader should always ensure that they override the AutoLoader->import() method.
If the module inherit from
Exporter like shown in the synopis section this is already taken care of. For class methods an empty
import would do nicely:
package MyClass;
use AutoLoader; # load stubs
@ISA=qw(AutoLoader);
sub import {} # hide AutoLoader::import
You can also set up autoloading by importing the AUTOLOAD function instead of inheriting from AutoLoader:
package MyClass; use AutoLoader; # load stubs *AUTOLOAD = \&AutoLoader::AUTOLOAD;
__END__ marker.
A module using such variables as package globals will
not work properly under the AutoLoader.
The vars pragma (see vars) may be used in such situations as an alternative to explicitly qualifying
all globals with the package namespace. Variables pre-declared with this
pragma will be visible to any autoloaded routines (but will not be
invisible outside the package, unfortunately).
__DATA__ marker rather than __END__. While this avoids the use of a hierarchy of disk files and the associated
open/close for each routine loaded, the SelfLoader suffers a disadvantage in the one-time parsing of the lines after __DATA__, after which routines are cached. SelfLoader
can also handle multiple packages in a file.
AutoLoader only reads code as it is requested, and in many cases should be faster, but requires a machanism like AutoSplit be used to create the individual files. The ExtUtils::MakeMaker will invoke AutoSplit automatically if the AutoLoader is used in a module source file.