def load_zcml(self, spec='configure.zcml', lock=threading.Lock()):
""" Load configuration from a :term:`ZCML` file into the
current configuration state. The ``spec`` argument is an
absolute filename, a relative filename, or a :term:`asset
specification`, defaulting to ``configure.zcml`` (relative to
the package of the method's caller)."""
package_name, filename = self._split_spec(spec)
if package_name is None: # absolute filename
package = self.package
else:
__import__(package_name)
package = sys.modules[package_name]
registry = self.registry
self.manager.push({'registry':registry, 'request':None})
context = self._ctx
if context is None:
context = self._ctx = self._make_context(self.autocommit)
# To avoid breaking people's expectations of how ZCML works, we
# cannot autocommit ZCML actions incrementally. If we commit actions
# incrementally, configuration outcome will be controlled purely by
# ZCML directive execution order, which isn't what anyone who uses
# ZCML expects. So we don't autocommit each ZCML directive action
# while parsing is happening, but we do make sure to pass
# execute=self.autocommit to xmlconfig.file below, which will cause
# the actions implied by the ZCML that was parsed to be committed
# right away once parsing is finished if autocommit is True.
context = GroupingContextDecorator(context)
context.autocommit = False
lock.acquire()
try:
context.package = package
xmlconfig.file(filename, package, context=context,
execute=self.autocommit)
finally:
lock.release()
self.manager.pop()
return registry
