wr-attrs 0.1.5

# wr-attrs


* Attributes are descriptors for classes and values for instances

class A(AttrContainer):
p = Attr()

a = A()

assert isinstance(A.p, Attr)
assert A.p.name == 'p'
assert A.p.default is None

assert a.p is None

* Attributes can be easily initialised

a = A(p=23)

assert isinstance(A.p, Attr)
assert A.p.default is None

assert a.p == 23

* Attributes are inherited

class B(A):
q = Attr()
r = Attr()

b = B(p=23, q=42)

assert B.p is A.p

assert b.p == 23
assert b.q == 42
assert b.r is None


* Attributes are registered in a collection.

b = B(q=42)

assert len(b.attrs) == 3
assert b.attrs.names == ['p', 'q', 'r']
assert list(b.attrs.values) == [('p', None), ('q', 42), ('r', None)]

assert b.attrs.q is B.q
assert b.attrs['q'] is B.q
assert b.attrs.get('q') == 42


* Attributes can have default values set in inherited classes without overwriting
the descriptor.

class C(B):
p = 0
q = 1

c = C()

assert c.p == 0
assert c.q == 1
assert c.r is None

assert C.p is B.p
assert C.q is B.q
assert C.r is B.r

* Attributes can have custom setters.

class D(C):
s = Attr()

@s.setter
def s(self, value):
self.attrs.set('s', value * 5)

d = D(s=0)
d.s = 5
assert d.s == 25