June 2002
Beginner
759 pages
80h 42m
English
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Modules
A module is a package defined in a
file with a name that is the same as the package’s. Perl locates
modules by searching the @INC
array, which contains a list of library directories. Perl’s use of
@INC is roughly comparable to the
Unix shell’s use of the PATH environment variable to locate executable
programs. @INC is defined when Perl
is built and can be supplemented with the -I
command-line option to Perl or with use
lib within a program.
When you refer to ModuleName
in your program, Perl searches in the directories listed in @INC for the module file
ModuleName.pm and uses the first one it finds.
When you refer to a module embedded in another package, such as
ParentPackage::ModuleName, Perl
looks for a ParentPackage/ subdirectory in the
@INC path, and for a
ModuleName.pm file in that subdirectory.
Every Perl installation includes a central lib directory. The actual pathname of this directory varies from system to system, but it’s commonly /usr/lib/perl or /usr/local/lib/perl. Looking at the central lib directory for your Perl distribution, you’ll see something like this:
% ls -aF /usr/local/lib/perl ./ I18N/ bigfloat.pl less.pm ../ IO/ bigint.pl lib.pm AnyDBM_File.pm IPC/ bigrat.pl locale.pm AutoLoader.pm Math/ blib.pm look.pl AutoSplit.pm Net/ cacheout.pl man/ Benchmark.pm Pod/ chat2.pl newgetopt.pl Bundle/ Search/ complete.pl open2.pl CGI/ SelectSaver.pm constant.pm open3.pl CGI.pm SelfLoader.pm ctime.pl perl5db.pl CPAN/ Shell.pm diagnostics.pm pod/ CPAN.pm Symbol.pm dotsh.pl ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.