96 lines
2.2 KiB
Python
96 lines
2.2 KiB
Python
"""
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A list subclass for Python 2 that behaves like Python 3's list.
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The primary difference is that lists have a .copy() method in Py3.
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Example use:
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>>> from builtins import list
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>>> l1 = list() # instead of {} for an empty list
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>>> l1.append('hello')
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>>> l2 = l1.copy()
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"""
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import sys
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import copy
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from future.utils import with_metaclass
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from future.types.newobject import newobject
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_builtin_list = list
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ver = sys.version_info[:2]
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class BaseNewList(type):
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def __instancecheck__(cls, instance):
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if cls == newlist:
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return isinstance(instance, _builtin_list)
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else:
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return issubclass(instance.__class__, cls)
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class newlist(with_metaclass(BaseNewList, _builtin_list)):
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"""
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A backport of the Python 3 list object to Py2
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"""
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def copy(self):
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"""
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L.copy() -> list -- a shallow copy of L
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"""
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return copy.copy(self)
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def clear(self):
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"""L.clear() -> None -- remove all items from L"""
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for i in range(len(self)):
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self.pop()
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def __new__(cls, *args, **kwargs):
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"""
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list() -> new empty list
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list(iterable) -> new list initialized from iterable's items
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"""
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if len(args) == 0:
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return super(newlist, cls).__new__(cls)
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elif type(args[0]) == newlist:
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value = args[0]
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else:
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value = args[0]
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return super(newlist, cls).__new__(cls, value)
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def __add__(self, value):
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return newlist(super(newlist, self).__add__(value))
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def __radd__(self, left):
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" left + self "
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try:
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return newlist(left) + self
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except:
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return NotImplemented
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def __getitem__(self, y):
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"""
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x.__getitem__(y) <==> x[y]
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Warning: a bug in Python 2.x prevents indexing via a slice from
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returning a newlist object.
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"""
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if isinstance(y, slice):
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return newlist(super(newlist, self).__getitem__(y))
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else:
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return super(newlist, self).__getitem__(y)
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def __native__(self):
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"""
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Hook for the future.utils.native() function
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"""
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return list(self)
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def __nonzero__(self):
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return len(self) > 0
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__all__ = ['newlist']
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