The App::Cache module lets an application cache data locally. There are a
few times an application would need to cache data: when it is retrieving
information from the network or when it has to complete a large calculation.
For example, the Parse::BACKPAN::Packages module downloads a file off the
net and parses it, creating a data structure. Only then can it actually
provide any useful information for the programmer. Parse::BACKPAN::Packages
uses App::Cache to cache both the file download and data structures,
providing much faster use when the data is cached. This module stores data
in the home directory of the user, in a dot directory. For example, the
Parse::BACKPAN::Packages cache is actually stored underneath
"~/.parse_backpan_packages/cache/". This is so that permisssions are not a
problem -- it is a per-user, per-application cache.