"""
A dict subclass for Python 2 that behaves like Python 3's dict
Example use:
>>> from builtins import dict
>>> d1 = dict() # instead of {} for an empty dict
>>> d2 = dict(key1='value1', key2='value2')
The keys, values and items methods now return iterators on Python 2.x
(with set-like behaviour on Python 2.7).
>>> for d in (d1, d2):
... assert not isinstance(d.keys(), list)
... assert not isinstance(d.values(), list)
... assert not isinstance(d.items(), list)
"""
import sys
from future.utils import with_metaclass
from future.types.newobject import newobject
_builtin_dict = dict
ver = sys.version_info
class BaseNewDict(type):
def __instancecheck__(cls, instance):
if cls == newdict:
return isinstance(instance, _builtin_dict)
else:
return issubclass(instance.__class__, cls)
class newdict(with_metaclass(BaseNewDict, _builtin_dict)):
"""
A backport of the Python 3 dict object to Py2
"""
if ver >= (3,):
# Inherit items, keys and values from `dict` in 3.x
pass
elif ver >= (2, 7):
items = dict.viewitems
keys = dict.viewkeys
values = dict.viewvalues
else:
items = dict.iteritems
keys = dict.iterkeys
values = dict.itervalues
def __new__(cls, *args, **kwargs):
"""
dict() -> new empty dictionary
dict(mapping) -> new dictionary initialized from a mapping object's
(key, value) pairs
dict(iterable) -> new dictionary initialized as if via:
d = {}
for k, v in iterable:
d[k] = v
dict(**kwargs) -> new dictionary initialized with the name=value pairs
in the keyword argument list. For example: dict(one=1, two=2)
"""
return super(newdict, cls).__new__(cls, *args)
def __native__(self):
"""
Hook for the future.utils.native() function
"""
return dict(self)
__all__ = ['newdict']
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