'Set the base path where resources will be extracted to, if needed.
If you do not call this routine before any extractions take place, the
path defaults to the return value of ``get_default_cache()``.  (Which
is based on the ``PYTHON_EGG_CACHE`` environment variable, with various
platform-specific fallbacks.  See that routine\'s documentation for more
details.)
Resources are extracted to subdirectories of this path based upon
information given by the ``IResourceProvider``.  You may set this to a
temporary directory, but then you must call ``cleanup_resources()`` to
delete the extracted files when done.  There is no guarantee that
``cleanup_resources()`` will be able to remove all extracted files.
(Note: you may not change the extraction path for a given resource
manager once resources have been extracted, unless you first call
``cleanup_resources()``.)'

def set_extraction_path(self, path):

    if self.cached_files:
        raise ValueError("Can't    change    extraction    path,    files    already    extracted")
    self.extraction_path = path
