Re: Comparing hash table objects

[Sam Steingold <sds@gnu.org>]

> * Stefan Monnier <zbaavre@veb.hzbagerny.pn> [2022-06-11 12:04:46 -0400]:
>
>> However, it will not help with the problem of comparing objects
>> containing hash tables. Unless those obejcts also define special
>> comparison function (which is inconvenient).
>
> This is an instance of a fairly general problem with Lisp's equality
> tests (and it's not really specific to Lisp, admittedly).

Sadly, this is true.

> Maybe a half-sane way to solve this problem is to provide a generic
> "equality driver" which takes an argument specifying which objects to
> compare for structural equality (i.e. where to keep recursing).

The way Python does it could be a good starting point:
unless a class defines __eq__ method, the comparison is Lisp eq.
So, if a class has structure, it should define the comparison method.
See https://docs.python.org/3/reference/datamodel.html#object.__eq__

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