Lisp mentality vs. Python mentality

[Ciprian Dorin, Craciun]

On Sat, Apr 25, 2009 at 11:30 AM, "Martin v. Löwis" <martin at v.loewis.de> wrote:
>>>>     Ok... Then what's pythonic? Please give a pythonic implementation...
>>> Use the builtin a==b, similar to (equal a b)
>>
>>     But how about extensibility?
> [...]
>
> I see that you allow for a different comparison function. I do wonder
> what the use case for this is - in what application do you have to
> compare two lists for equality, and the item's __eq__ is inappropriate?
> What would break if you fix the item's __eq__, instead of writing
> your own comparison algorithm?
>
> [...]

    A practical example: I have lists that contain strings, but I want
to compare them in an case-insensitive way... Should I update the
__eq__ method (for str class) and break almost everything? Can I write
now a == b? Nop... I need the loop you've just mentioned in all the
places where the comparison changes just in the operator, not in the
algorithm... (I would say this is bad coding practice...)