test_interface.py 文件源码

def test_invariant_as_decorator():
        """Invaiants can be deined in line

          >>> class IRange(interface.Interface):
          ...     min = interface.Attribute("Lower bound")
          ...     max = interface.Attribute("Upper bound")
          ...
          ...     @interface.invariant
          ...     def range_invariant(ob):
          ...         if ob.max < ob.min:
          ...             raise Invalid('max < min')


          >>> class Range(object):
          ...     interface.implements(IRange)
          ...
          ...     def __init__(self, min, max):
          ...         self.min, self.max = min, max

          >>> IRange.validateInvariants(Range(1,2))
          >>> IRange.validateInvariants(Range(1,1))
          >>> IRange.validateInvariants(Range(2,1))
          Traceback (most recent call last):
          ...
          Invalid: max < min


        """