[Python-Dev] PyList API missing PyList_Pop() and PyList_Delete

Raymond Hettinger python at rcn.com
Fri Oct 24 15:01:09 EDT 2003

> -----Original Message-----
> > The bummer is that this call is effectively used in a loop and runs
> > for every data element in an iterable.  Something like pop() has
such a
> > tiny granularity that its runtime is overwhelmed by the lookup time
> > call it this way.  For this reason, I think PyList_Pop() warrants
> > inclusion in the API much more than low granularity methods like
> > PyList_Reverse() or PyList_Sort().
> But it's easy to simulate a pop, writing the C equivalent of
>     x = lst[len(lst)-1]
>     del lst[len(lst)-1 : len(lst)]

 . . .
>     PyList_SetSlice(lst, n-1, n, NULL);

There's the new piece of information.  I didn't know that the final
argument could be NULL and creating/destroying and empty list for the
arg was unpleasant.  I'll add that info to the API docs.

> I see no need to add this to the public API just yet (it would have to
> be more flexible to allow lst.pop(n), do more arg checks, etc.).

Yes.  See if more requestors come along.

Surely, I was not the first to want to use PyLists as append/pop stacks
for PyObjects.



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