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Copy pathbuiltin_property.py
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102 lines (83 loc) · 1.64 KB
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# test builtin property
# create a property object explicitly
property()
property(1, 2, 3)
# use its accessor methods
p = property()
p.getter(1)
p.setter(2)
p.deleter(3)
# basic use as a decorator
class A:
def __init__(self, x):
self._x = x
@property
def x(self):
print("x get")
return self._x
a = A(1)
print(a.x)
try:
a.x = 2
except AttributeError:
print("AttributeError")
# explicit use within a class
class B:
def __init__(self, x):
self._x = x
def xget(self):
print("x get")
return self._x
def xset(self, value):
print("x set")
self._x = value
def xdel(self):
print("x del")
x = property(xget, xset, xdel)
b = B(3)
print(b.x)
b.x = 4
print(b.x)
del b.x
# full use as a decorator
class C:
def __init__(self, x):
self._x = x
@property
def x(self):
print("x get")
return self._x
@x.setter
def x(self, value):
print("x set")
self._x = value
@x.deleter
def x(self):
print("x del")
c = C(5)
print(c.x)
c.x = 6
print(c.x)
del c.x
# a property that has no get, set or del
class D:
prop = property()
d = D()
try:
d.prop
except AttributeError:
print('AttributeError')
try:
d.prop = 1
except AttributeError:
print('AttributeError')
try:
del d.prop
except AttributeError:
print('AttributeError')
# properties take keyword arguments
class E:
p = property(lambda self: 42, doc="This is truth.")
# not tested for because the other keyword arguments are not accepted
# q = property(fget=lambda self: 21, doc="Half the truth.")
print(E().p)