Pythonically create a string representation of object with python literals

Question

I have an object that's constructor accepts *kwargs and sets them as atributes.

class Observable(object):
    def __init__(self, **kwargs):
        for key in kwargs.keys():
            setattr(self, key, kwargs[key])

I want print to represent the object in the following way:

>>> obs = Observable(foo=1, bar=5, _bazz=12, name='Amok', props=('One', 'two'))
>>> print(x)
Observable(bar=5, foo=1, name='Amok', props=('One', 'two'))

I tried to add a custom __repr__:

class Observable(object):
    def __init__(self, **kwargs):
        for key in kwargs.keys():
            setattr(self, key, kwargs[key])

    def __repr__(self):
        atribs = [(atrib,  self.__dict__[atrib]) for atrib in self.__dict__.keys() if not '_' == atrib[0]]
        atrib_strs = []
        for atrib, val in atribs:
            atrib_strs.append('{}={}'.format(atrib, val))

        out_str = '{}({})'.format(self.__class__.__name__, ', '.join(atrib_strs))
        return out_str

For the input above it prints:

Observable(foo=1, bar=5, name=Amok, props=('One', 'two'))

My concern is that I have Amok instead of 'Amok'. I can add a type check for strings, but perhaps there is a way to get a correct string representation of any python type? Maybe a standard library function?

I haven't looked into the question but my ocd is killing me to see pytonically instead of Pythonic or Pythonically. — void
– void, Commented Jun 22, 2017 at 7:09

Chris · Accepted Answer · 2017-06-22 07:16:13Z

3

A simple way to accomplish this would be to call every attribute's value's __repr__() via repr(). That way, each string representation is guaranteed to be displayed.

>>> class Observable(object):
    def __init__(self, **kwargs):
        for key in kwargs.keys():
            setattr(self, key, kwargs[key])

    def __repr__(self):
        atribs = [(atrib,  self.__dict__[atrib]) for atrib in self.__dict__.keys() if not '_' == atrib[0]]
        atrib_strs = []
        for atrib, val in atribs:
            atrib_strs.append('{}={}'.format(atrib, repr(val))) # add repr() call

        out_str = '{}({})'.format(self.__class__.__name__, ', '.join(atrib_strs))
        return out_str

>>> ob = Observable(foo=1, bar=5, _bazz=12, name='Amok', props=('One', 'two'))
>>> print(ob)
Observable(foo=1, name='Amok', props=('One', 'two'), bar=5)
>>>

edited Jun 22, 2017 at 7:16

answered Jun 22, 2017 at 7:10

Chris

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2 Comments

Azat Ibrakov Over a year ago

how about not using dict.keys/getting value and use dict.items/dict.iteritems instead?

Chris Over a year ago

@AzatIbrakov Because he doesn't want to include "private" variables in the representation. Although his code could be improved., I didn't really try much.

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