Series not honoring class __repr__ or __str__

Code Sample, a copy-pastable example if possible

class foo(dict):
    def __init__(self, iterable=None, **kwargs):
        if iterable is None:
            iterable = ()
        super(foo, self).__init__(iterable)
        self.update(kwargs)
    def __repr__(self):
        return ",".join(self.keys())
    def __str__(self):
        return ",".join(self.keys())

f = foo({'alpha' : 'b',
    'beta' : 'c'})

import pandas as pd
pd.DataFrame(data=[['A', 1, f]], columns=['D', 'F', 'G'])

Problem description

For a given series with a custom object, I want to control the content when displayed via print or displaying on ipython notebooks. The object foo is a simple class that have the __str__ and __repr__ overwritten, but still displays the object’s dictionary content, not the view I want to show the end users. How do I control that?

Expected Output

alpha,beta

what I get is:

{'alpha': 'b', 'beta': 'c'}

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line] INSTALLED VERSIONS

commit: None python: 3.5.4.final.0 python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: Intel64 Family 6 Model 94 Stepping 3, GenuineIntel byteorder: little LC_ALL: None LANG: None LOCALE: None.None

pandas: 0.21.1 pytest: 3.3.1 pip: 9.0.1 setuptools: 38.2.4 Cython: None numpy: 1.11.2 scipy: 0.18.1 pyarrow: None xarray: None IPython: 5.3.0 sphinx: 1.6.3 patsy: 0.4.1 dateutil: 2.6.1 pytz: 2017.3 blosc: None bottleneck: None tables: None numexpr: None feather: None matplotlib: 1.5.3 openpyxl: None xlrd: 1.1.0 xlwt: 1.3.0 xlsxwriter: None lxml: None bs4: 4.6.0 html5lib: 0.999 sqlalchemy: None pymysql: None psycopg2: None jinja2: 2.9.6 s3fs: None fastparquet: None pandas_gbq: None pandas_datareader: None

[lgharibashvili]

Quick dirty patch for those who cannot wait for the fix:

from pandas.io.formats import printing as pd_printing
pd_printing.is_sequence = lambda obj: False

[achapkowski]

@TomAugspurger not subclassing from dict is not an option since the other classes are established. Is there a way to override the print function (not optimal) or set something on the class to say hey use the __repr__