text: """Internal constants."""
  
  import os
  import sys
  
  from snakeoil import mappings
  
  _reporoot = os.path.realpath(__file__).rsplit(os.path.sep, 3)[0]
  _module = sys.modules[__name__]
  
  try:
      # This is a file written during installation;
      # if it exists, we defer to it. If it doesn't, then we're
      # running from a git checkout or a tarball.
      from . import _const as _defaults
  except ImportError:  # pragma: no cover
      _defaults = object()
  
  
  def _GET_CONST(attr, default_value):
      consts = mappings.ProxiedAttrs(_module)
      default_value %= consts
      return getattr(_defaults, attr, default_value)
  
  
  # determine XDG compatible paths
  for xdg_var, var_name, fallback_dir in (
          ('XDG_CONFIG_HOME', 'USER_CONFIG_PATH', '~/.config'),
          ('XDG_CACHE_HOME', 'USER_CACHE_PATH', '~/.cache'),
          ('XDG_DATA_HOME', 'USER_DATA_PATH', '~/.local/share')):
      setattr(
          _module, var_name,
          os.environ.get(xdg_var, os.path.join(os.path.expanduser(fallback_dir), 'pkgcheck')))
  
  REPO_PATH = _GET_CONST('REPO_PATH', _reporoot)
  DATA_PATH = _GET_CONST('DATA_PATH', '%(REPO_PATH)s/data')
  
  USER_CACHE_DIR = getattr(_module, 'USER_CACHE_PATH')
  USER_CONF_FILE = os.path.join(getattr(_module, 'USER_CONFIG_PATH'), 'pkgcheck.conf')
  SYSTEM_CONF_FILE = '/etc/pkgcheck/pkgcheck.conf'
  BUNDLED_CONF_FILE = os.path.join(DATA_PATH, 'pkgcheck.conf')
  