__getattr__()
and __str__()
for an object are found on its class, so if you want to customize those things for a class, you need the class-of-a-class. A metaclass.
class FooType(type):
def _foo_func(cls):
return 'foo!'
def _bar_func(cls):
return 'bar!'
def __getattr__(cls, key):
if key == 'Foo':
return cls._foo_func()
elif key == 'Bar':
return cls._bar_func()
raise AttributeError(key)
def __str__(cls):
return 'custom str for %s' % (cls.__name__,)
class MyClass:
__metaclass__ = FooType
# in python 3:
# class MyClass(metaclass=FooType):
# pass
print MyClass.Foo
print MyClass.Bar
print str(MyClass)
printing:
foo!
bar!
custom str for MyClass
And no, an object can't intercept a request for a stringifying one of its attributes. The object returned for the attribute must define its own __str__()
behavior.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…