dir vs hasattr

result

i: a
True
r: False
True
---
i: b
True
r: ""
True
---
i: c
True
r: []
True
---
i: d
True
r: NotImplementedError()
False
---
i: e
True
r: None
False
---

test.py

import inspect

class X:
    @property
    def a(self):
        print 'r: False'
        return False

    @property
    def b(self):
        print 'r: ""'
        return ''

    @property
    def c(self):
        print 'r: []'
        return []

    @property
    def d(self):
        print 'r: NotImplementedError()'
        raise NotImplementedError()
    
    @property
    def e(self):
        print 'r: None'
        raise None

x = X()

for i in dir(x):
    if i[0] != '_':
        print 'i:', i
        print i in dir(x)
        print hasattr(x, i)
        print '---'