micropython/tests/basics/class_descriptor.py

class Descriptor:
    def __get__(self, obj, cls):
        print('get')
        print(type(obj) is Main)
        print(cls is Main)
        return 'result'

    def __set__(self, obj, val):
        print('set')
        print(type(obj) is Main)
        print(val)

    def __delete__(self, obj):
        print('delete')
        print(type(obj) is Main)

class Main:
    Forward = Descriptor()

m = Main()
try:
    m.__class__
except AttributeError:
    # Target doesn't support __class__.
    print("SKIP")
    raise SystemExit

r = m.Forward
if 'Descriptor' in repr(r.__class__):
    # Target doesn't support descriptors.
    print('SKIP')
    raise SystemExit

# Test assignment and deletion.

print(r)
m.Forward = 'a'
del m.Forward

# Test that lookup of descriptors like __get__ are not passed into __getattr__.


class NonDescriptor:
    def __getattr__(self, attr):
        print("getattr", attr)


class TestClass:
    non_descriptor = NonDescriptor()


print(isinstance(TestClass().non_descriptor, NonDescriptor))

t = TestClass()
t.non_descriptor = 123
print(t.non_descriptor)

try:
    del TestClass().non_descriptor
except AttributeError:
    print("AttributeError")