包装对象的最佳pythonic方法是什么？

Question

I would like to be able to wrap any object in Python. The following does not seem to be possible, would you know why?

class Wrapper:
    def wrap(self, obj):
        self = obj

a = list()
b = Wrapper().wrap(a)
# can't do b.append

Thank you!

Answer 1

Try with the getattr python magic :

class Wrapper:
    def wrap(self, obj):
        self.obj = obj
    def __getattr__(self, name):
        return getattr(self.obj, name)

a = list()
b = Wrapper()
b.wrap(a)

b.append(10)

Answer 2

Perhaps what you are looking for, that does the job you are looking to do, much more elegantly than you are trying to do it in, is:

Alex Martelli 's Bunch Class .

class Bunch:
    def __init__(self, **kwds):
    self.__dict__.update(kwds)

# that's it!  Now, you can create a Bunch
# whenever you want to group a few variables:

point = Bunch(datum=y, squared=y*y, coord=x)

# and of course you can read/write the named
# attributes you just created, add others, del
# some of them, etc, etc:
if point.squared > threshold:
    point.isok = 1

There are alternative implementations available in the linked recipe page.

Answer 3

You're just referencing the variable self to be a certain object in wrap(). When wrap() ends, that variable is garbage collected.

You could simply save the object in a Wrapper attribute to achieve what you want

Answer 4

You can also do what you want by overriding new:

class Wrapper(object):
    def __new__(cls, obj):
        return obj
t = Wrapper(list())
t.append(5)