def load_setting(key):
# Just some dummy values for demo
if key == 'key':
return '123123'
elif key == 'limit':
return 123123
elif key == 'dummylist':
return [1, 2, 3, 4, 5]
elif key == 'crap':
return {'good': "boy"}
def superlazy(key, default):
class T(type(default)):
@staticmethod
def __loader__():
ret = load_setting(key)
if ret:
setattr(T, '__cache__', ret)
delattr(T, '__loader__')
def force(k, v):
def _wrapper(*args, **kwargs):
if hasattr(T, '__loader__'):
T.__loader__()
if hasattr(T, '__cache__'):
c = T.__cache__
func = getattr(c, k)
return func(*args[1:], **kwargs)
return v(*args, **kwargs)
return _wrapper
t = T(default)
for k, v in type(default).__dict__.iteritems():
if (k in ['__doc__']): continue
setattr(T, k, force(k, v))
return t
# Lazy string
a = superlazy("key", 'hahahaha')
print a, isinstance(a, str)
# Lazy int
b = superlazy("limit",9)
print 1 + b, isinstance(b, int)
print str(b)
# Lazy list
c = superlazy("dummylist", [1, 2, 3])
print c
print c[0]
print len(c)
# Lazy dict
d = superlazy("crap", {'a': 1, 'b': 2, 'c': 3})
print isinstance(d, dict)
print d
print d.get('a')
# Not existed lazy int, default value is used
e = superlazy("wer", 321)
print isinstance(e, int)
print e
