[Python-Dev] Partial function application 'from the right' (original) (raw)

Ben North ben at redfrontdoor.org
Tue Feb 3 14:44:53 CET 2009

Hi,

Thanks for the further responses. Again, I'll try to summarise:

Scott David Daniels pointed out an awkward interaction when chaining partial applications, such that it could become very unclear what was going to happen when the final function is called:

If you have: def button(root, position, action=None, text='*', color=None): ... ... bluebutton = partial(button, myroot, color=(0,0,1))

Should partialright(bluebutton, 'red') change the color or the text?

Calvin Spealman mentioned a previous patch of his which took the 'hole' approach, i.e.:

[...] my partial.skip patch, which allows the following usage:

splitone = partial(str.split, partial.skip, 1)

This would solve my original problems, and, continuing Scott's example,

def on_clicked(...): ...

_ = partial.skip clickable_blue_button = partial(blue_button, _, on_clicked)

has a clear enough meaning I think:

clickable_blue_button('top-left corner') = blue_button('top-left corner', on_clicked) = button(my_root, 'top-left corner', on_clicked, color=(0,0,1))

Calvin's idea/patch sounds good to me, then. Others also liked it. Could it be re-considered, instead of the partial_right idea?

Ben.

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