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Keep object extended from dict/list intact

See original GitHub issue

Hi @cdgriffith,

I am the one who proposed ordered_box.
I was recently bothered by Box turning some objects that are inherited from dict/list into Box/BoxList.
Consider the following codes:

from box import Box

class MyList(list): 
    def sq(self):
        return [x*x for x in self]
b = Box(a = MyList([1,2,4]))
# AttributeError: 'BoxList' object has no attribute 'sq'
# Expect [1,4,16]

I extended list to add some extra methods for convenience. However, when it was changed by Box into a BoxList, then I lost my method sq. Is it possible to keep the objects of extended dict/list intact, but convert the raw dict/lists?

One simple way is to check the __bases__, if it is (object, ) then it should be a raw dict/list:

def _israwinstance(obj, klass):
    return isinstance(obj, klass) and obj.__class__.__bases__ \
       and obj.__class__.__bases__[0] is object

Thanks, Panwen

Issue Analytics

  • State:closed
  • Created 4 years ago
  • Comments:5 (5 by maintainers)

github_iconTop GitHub Comments

pwwangcommented, Apr 25, 2019

I understood your concern about not converting those subclasses of dict in this way, for example, OrderedDict.
What about we enabling a kwarg setting, say box_intact_types, to put those types, and excluding them in __convert_and_store? My case would be then:

from box import Box

class MyList(list): 
    def sq(self):
        return [x*x for x in self]
b = Box(a = MyList([1,2,4]), box_intact_types = (MyList, ))
# [1,4,16]

In __convert_and_store while checking types, we could do:

if isinstance(value, tuple(self._box_config['intact_types'])):
    return value
Read more comments on GitHub >

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