[Python-Dev] Re: Re: lists v. tuples

[Guido van Rossum]

> However, I'm slightly dubious about the x.sort(lt=f) vs x.sort(cmp=f)
> technique because it doesn't generalize terribly well.
> 
> If I want to write a function that takes a comparison function as an
> argument, and eventualy passes that function to sort, what do I do?
> Something like this?
> 
>         def myfun(foo, bar, lt=None, cmp=None):
>                 # ...
>                 x.sort(lt=lt, cmp=cmp)
>                 # ...
> 
> and assume that sort will use None as its defaults also?  Or must I
> write
> 
>                 if lt==None:
>                         x.sort(cmp=cmp)
>                 else:
>                         x.sort(lt=lt)
> 
> Either way it's inconvenient.

Given that (if we add this) the cmp argument will be deprecated,
myfun() should take a 'lt' comparison only.

> So I wonder if it might be better, as a way of allowing sort to take
> two different types of comparison functions, to distinguish between
> them by making them different types.

But Python doesn't do types that way.

--Guido van Rossum (home page: http://www.python.org/~guido/)