Sort with extra variables

[Alex Martelli]

Thomas Dybdahl Ahle <lobais at gmail.com> wrote:

> I have a sort function in a python chess program.
> Currently it looks like this:
> 
> def sortMoves (board, table, ply, moves):
>     f = lambda move: getMoveValue (board, table, ply, move)
>     moves.sort(key=f, reverse=True)
>     return moves
> 
> However I'd really like not to use the lambda, as it slows down the code.
> 
> I've thought about saving the extra variables in the global space, but it
> really feals ugly.
> 
> Do you have any ideas how I can sort these moves the fastest?

Maybe

  moves.sort(key=functool.partial(board, table, ply), reverse=True)

might be a bit faster?  Not sure, but maybe worth trying.

If not, a bit faster (nothing major) might be

  def f(move, board=board, table=table, ply=ply):
      return getMoveValue(board, table, ply, move)

the small advantage here would be to use the lexically scoped variable
lookup just once (at nested-def time) with the three names being then
looked up as locals in the len(moves) call to f...


Alex