Loads the user's preferences from the preference file.
If the user is on a Windows machine, the file will be in the PEAR_CONFIG_SYSCONFIG directory and named ppurc.ini. If the user is on any other operating system, the preferences file will be stored in the user's home directory as the file .ppurc. The file contains a serialized array of preferences for each package that has been checked for updates so far.
Note: Since version 0.7.0, you could also choose another directory and name for your preference file. Use then the optional parameter $pref_file.
throws PEAR_PACKAGEUPDATE_ERROR_PREFFILE_READACCESS, when user's preference file has no READ access right.
throws PEAR_PACKAGEUPDATE_ERROR_PREFFILE_CORRUPTED, when user's preference file has invalid contents.
throws PEAR_PACKAGEUPDATE_ERROR_INVALIDINIFILE, when user's preference file given by parameter $pref_file does not exist.