Class Command

Start the command. This method should return a Deferred that will fire when the command has completed. The Deferred's argument will be ignored.

This method should be overridden by subclasses.

Override this in a subclass to allow commands to be interrupted. May be called multiple times, test and set self.interrupted=True if this matters.

Special descriptor for class __provides__

The descriptor caches the implementedBy info, so that
we can get declarations for objects without instance-specific
interfaces a bit quicker.

For example:

  >>> from zope.interface import Interface
  >>> class IFooFactory(Interface):
  ...     pass
  >>> class IFoo(Interface):
  ...     pass
  >>> class C(object):
  ...     implements(IFoo)
  ...     classProvides(IFooFactory)
  >>> [i.getName() for i in C.__provides__]
  ['IFooFactory']

  >>> [i.getName() for i in C().__provides__]
  ['IFoo']

__implemented__

Value:

<implementedBy buildslave.commands.base.Command>