pierre@1: 
pierre@1: Cache hook format:
pierre@1:   $cache['hook_name'] = array(
pierre@1:     'weight' => integer, // optional
pierre@1:     'file' => '/full/path/to/include/file',
pierre@1:     'function' => 'function_name',
pierre@1:   );
pierre@1: 
pierre@1: Supported hooks:
pierre@1: 
pierre@1:  - hook_init
pierre@1:     Alter which advertisements are selecting from.
pierre@1: 
pierre@1:  - hook_filter
pierre@1:     Filter out invalid advertisements.
pierre@1: 
pierre@1:  - hook_select
pierre@1:     Alter how advertisements are selected.
pierre@1: 
pierre@1: OLD README (this may not be accurate anymore):
pierre@1: TODO: Update.
pierre@1: Ad caches are defined through external modules.  Ad caches are composed of a
pierre@1: module 'ad_cache_TYPE.module' and an include file 'ad_cache_TYPE.inc' that live
pierre@1: in the 'cache/TYPE' subdirectory where 'TYPE' is replaced with the type of
pierre@1: cache.  For example, the included file cache lives in 'cache/file'.
pierre@1: 
pierre@1: The ad_cache_TYPE.inc file must have a function named ad_cache_TYPE() which is
pierre@1: used to display ads.  It can optionally include a function titled
pierre@1: ad_cache_TYPE_variables used to extract any necessary variables from the global
pierre@1: $_GET array (this can also be used to override values that would normally be
pierre@1: set from $_GET).  Any functions used by this code without bootstrapping Drupal
pierre@1: should also be in this file.
pierre@1: 
pierre@1: The ad_cache_TYPE.module file should define the drupal _help() hook so the
pierre@1: module can be enabled.  It should also define the _adcacheapi() hook allowing
pierre@1: for configuration and processing.  Any functions used by this code after
pierre@1: bootstrapping Drupal should also be in this module.
pierre@1: 
pierre@1: Refer to cache/file/* for an implementation example.