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8.46. CPAN

Lets you access CPAN; search for a module, a bundle, an author, or a distribution; download a module or distribution; install it; and make it. The CPAN module can be used either interactively from the command line or programmatically:

perl -MCPAN -eshell;          # Run from the command line

or:

use CPAN;

my $obj = CPAN::Shell->install('ExtUtils::MakeMaker');

This section describes the use of the CPAN module from a program. See Chapter 2, "Installing Perl" for information on using it interactively and for details of the available commands. These commands, available interactively from the shell, are methods of the class CPAN::Shell. From a program, they are available both as methods (e.g., CPAN::Shell->install(...)) and as functions in the calling package (e.g., install(...)).

Each of the commands that produce listings of modules (r, autobundle, and u) returns a list of the IDs of all modules within the list. The IDs of all objects available within a program are strings that can be expanded to the corresponding real objects with the CPAN::Shell->expand("Module",@things) method. expand returns a list of CPAN::Module objects according to the @things arguments. In scalar context, it returns only the first element of the list.

8.46.1. Session and Cache Managers

The CPAN module contains a session manager, which keeps track of objects that have been fetched, built, and installed in the current session. No status is retained between sessions.

There is also a cache manager, which keeps track of disk space used and deletes extra space. The cache manager keeps track of the build directory, $CPAN::Config->{build_dir}, and uses a simple FIFO mechanism to delete directories below build_dir when they grow bigger than $CPAN::Config->{build_cache}.

The original distribution files are kept in the directory $CPAN::Config->{keep_source_where}. This directory is not covered by the cache manager but must be controlled by the user. If the same directory is used as both build_dir and keep_source_where, your sources are deleted with the same FIFO mechanism.



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