[Python-Dev] Bad interaction of __index__ and sequence repeat

[David Hopwood]

Armin Rigo wrote:
> Hi,
> 
> There is an oversight in the design of __index__() that only just
> surfaced :-(  It is responsible for the following behavior, on a 32-bit
> machine with >= 2GB of RAM:
> 
>     >>> s = 'x' * (2**100)       # works!
>     >>> len(s)
>     2147483647
> 
> This is because PySequence_Repeat(v, w) works by applying w.__index__ in
> order to call v->sq_repeat.  However, __index__ is defined to clip the
> result to fit in a Py_ssize_t.

Clipping the result sounds like it would *never* be a good idea. What was
the rationale for that? It should throw an exception.

-- 
David Hopwood <david.nospam.hopwood at blueyonder.co.uk>