GH677 Allow pd.RangeIndex to be initialized with range

[loicdiridollou]

• Closes pd.RangeIndex should accept range as the first argument #677
• Tests added: Please use assert_type() to assert the type of any return value

[loicdiridollou]

/pandas_nightly

[twoertwein]

Happy to merge or wait if you want to remove __init__ first

[loicdiridollou]

Happy to merge or wait if you want to remove __init__ first

I deleted the __init__ method, just waiting for CI to finish but it is looking ready from a code perspective.

[twoertwein]

Thanks @loicdiridollou !

[Dr-Irv]

FYI, I think we should have kept __init__() and deleted __new__(). In the stubs, we only need to have __new__() if we want to have different overloads that produce different results. Otherwise __init__() is sufficient.

Admittedly, we're inconsistent in the stubs about that. There are times we use __new__() instead of __init__()

[twoertwein]

Admittedly, we're inconsistent in the stubs about that. There are times we use __new__() instead of __init__()

If we want to become more stubtest compatible (aligning pandas and pandas-stubs), we should use which ever constructor pandas uses, at least when possible.