def _add_tween(self, tween_factory, under=None, over=None, explicit=False):
if not isinstance(tween_factory, string_types):
raise ConfigurationError(
'The "tween_factory" argument to add_tween must be a '
'dotted name to a globally importable object, not %r' %
tween_factory)
name = tween_factory
if name in (MAIN, INGRESS):
raise ConfigurationError('%s is a reserved tween name' % name)
tween_factory = self.maybe_dotted(tween_factory)
for t, p in [('over', over), ('under', under)]:
if p is not None:
if not is_string_or_iterable(p):
raise ConfigurationError(
'"%s" must be a string or iterable, not %s' % (t, p))
if over is INGRESS or is_nonstr_iter(over) and INGRESS in over:
raise ConfigurationError('%s cannot be over INGRESS' % name)
if under is MAIN or is_nonstr_iter(under) and MAIN in under:
raise ConfigurationError('%s cannot be under MAIN' % name)
registry = self.registry
introspectables = []
tweens = registry.queryUtility(ITweens)
if tweens is None:
tweens = Tweens()
registry.registerUtility(tweens, ITweens)
def register():
if explicit:
tweens.add_explicit(name, tween_factory)
else:
tweens.add_implicit(name, tween_factory, under=under, over=over)
discriminator = ('tween', name, explicit)
tween_type = explicit and 'explicit' or 'implicit'
intr = self.introspectable('tweens',
discriminator,
name,
'%s tween' % tween_type)
intr['name'] = name
intr['factory'] = tween_factory
intr['type'] = tween_type
intr['under'] = under
intr['over'] = over
introspectables.append(intr)
self.action(discriminator, register, introspectables=introspectables)