all Python 3inspectfunction

inspect.isdatadescriptor()

descriptors

Checks that an object is a data descriptor: it has __set__ or __delete__ (property, __slots__ entries, attributes of C types).

Syntax

inspect.isdatadescriptor(object) -> bool

The difference from a method descriptor is priority: a data descriptor in the class beats the instance __dict__, so a property cannot be shadowed by obj.p = 1; the setter runs or you get AttributeError. A plain method is not a data descriptor: assigning a.m = ... just hides it behind an instance attribute. Check the object from the class (A.__dict__['p']), not the value read through an instance.

Examples

import inspect
class A:
    @property
    def p(self):
        return 1
    def m(self):
        return 2
print(inspect.isdatadescriptor(A.__dict__['p']))  # → True
print(inspect.isdatadescriptor(A.__dict__['m']))  # → False
a = A()
a.m = 'спрятан'
print(a.m)  # → спрятан
try:
    a.p = 5
except AttributeError:
    print('property не перекрыть')  # → property не перекрыть

See also

Common errors

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