[Python-ideas] Add kwargs to built-in function object

[Leif Walsh]

On Thu, 22 May 2008, Bruce Leban wrote:
> Tuples are immutable. Lists are mutable. The reason I suggest making it
> variable length is so that it supports the full list semantics and you could
> for example create a NamedList object with no values and then add values to
> it (ditto for NamedDict).

I might be wrong here, but I think one of the reasons NamedTuple was
decided upon (its immutability, specifically) was a performance issue.
It's a lot easier to optimize a struct when you know exactly what its
fields are.  I think making a mutable one of these is really not
offering all that much advantage to anyone in a large number of cases.

> Well, I think the "Named" aspect is important. For example, repr(x) tells
> you the name. I can tell if two objects are the same type.

Well, right.  That's the point of a struct-style class.  You name it
whatever you would like.

> Also the NamedDict supports attribute access to the specific fields you've
> declared and no others. So it's not a freewheeling object that you can add
> any attribute to it. It's just a lightweight way to create an object backed
> by a dict (just as NamedTuple is).

I'm confused.  I thought you said you wanted mutability.  Now you can
only have the fieldnames you specify in the beginning?  This is not
really how a dict usually operates.

That said, you can mess with __slots__ all you want in your free time,
but I think we're straying pretty far from "one obvious way" here.

-- 
Cheers,
Leif