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12.11. Speeding Up Module Loading with Autoloader
12.11.1. Problem
You want
to use the AutoLoader module.
12.11.2. Solution
The easiest solution is to use the h2xs facility
to create a directory and all the files you need. Here we assume you
have your own directory, ~/perllib/, which
contains your personal library modules.
% h2xs -Xn Sample
% cd Sample
% perl Makefile.PL LIB=~/perllib
% (edit Sample.pm)
% make install
12.11.3. Discussion
The AutoLoader addresses the same performance issues as the
SelfLoader. It also provides stub functions that get replaced by real
ones the first time they''re called. But instead of looking for
functions all in the same file, hidden below a _ _DATA_
_ marker, the AutoLoader expects to find the real
definition for each function in its own file. If your
Sample.pm module had two functions,
foo and bar, then the
AutoLoader would expect to find them in
Sample/auto/foo.al and
Sample/auto/bar.al, respectively. Modules
employing the AutoLoader load faster than those using the SelfLoader,
but at the cost of extra files, disk space, and complexity.This setup sounds complicated. If you were doing it manually, it
probably would be. Fortunately, h2xs helps out
tremendously here. Besides creating a module directory with templates
for your Sample.pm file and other files you
need, it also generates a Makefile that uses the AutoSplit module to
break your module''s functions into little files, one function per
file. The make install rule
installs these so they will be found automatically. All you have to
do is put the module functions down below an _ _END_
_ line (rather than a _ _DATA_ _ line as
in SelfLoader) that h2xs already created.As with the SelfLoader, it''s easier to develop and test your module
without the AutoLoader. Just comment out the _ _END_
_ line while developing it.The same restrictions about invisibility of file lexicals that apply
to modules using the SelfLoader also apply when using the AutoLoader,
so using file lexicals to maintain private state doesn''t work. If
state is becoming that complex and significant an issue, consider
writing an object module instead of a traditional one.
12.11.4. See Also
The documentation for the standard module AutoLoader;
h2xs(1); Recipe 12.10
