[Python-Dev] shrinking dicts

[Vladimir Marangozov]

M.-A. Lemburg wrote:
> 
> [me]
> > Any other ideas on how to deal with this? Thoughts, comments?
> 
> I think that integrating this into the C code is not really that
> effective since the situation will not occur that often and then
> it often better to let the programmer decide rather than integrate
> an automatic downsize.

Agreed that the situation is rare. But if it occurs, its Python's
responsability to manage its data structures (and system resources)
efficiently. As a programmer, I really don't want to be bothered with
internals -- I trust the interpreter for that. Moreover, how could
I decide that at some point, some dict needs to be resized in my
fairly big app, say IDLE?

> 
> You can call dict.update({}) to force an internal
> resize (the empty dictionary can be made global since it is not
> manipulated in any way and thus does not cause creation overhead).

I know that I can force the resize in other ways, but this is not
the point. I'm usually against the idea of changing the programming
logic because of my advanced knowledge of the internals.

> 
> Perhaps a new method .resize(approx_size) would make this even
> clearer. This would also have the benefit of allowing a programmer
> to force allocation of the wanted size, e.g.
> 
> d = {}
> d.resize(10000)
> # Insert 10000 items in a batch insert

This is interesting, but the two ideas are not mutually excusive.
Python has to dowsize dicts automatically (just the same way it doubles
the size automatically). Offering more through an API is a plus for
hackers. ;-)

-- 
       Vladimir MARANGOZOV          | Vladimir.Marangozov@inrialpes.fr
http://sirac.inrialpes.fr/~marangoz | tel:(+33-4)76615277 fax:76615252