[Python-Dev] Re: What is PEP309?

[Peter Harris]

Aahz wrote:

>What's PEP309?
>
>(People reading python-dev do not all have all PEP numbers memorized,
>and it's not reasonable to expect everyone to go look them up when it
>would take you only a few moments to save everyone else time.)
>  
>
OK, sorry about that.

PEP309 is for a class that emulates partial function application (a bit 
like currying in
languages that do it that way, but not exactly).

It lets you make callable wrappers round a callable object, with some 
arguments 'frozen in'.

#e.g.  classes and functions can both be used:
win = Tkinter.Tk()   # my window
blueButn = partial(Tkinter.Button, win, fg='blue')   # factory for blue 
buttons in my window
def callback(name):
    print name,"pressed"
b1 = blueButn(text="Hello", command=partial(callback,"hello"))
b2 = blueButn(text="Goodbye", command=partial(callback,"goodbye"))

The PEP proposes a module 'functional' for stuff (like partial) that 
operates on or returns
other functions.  I expect there are a few things that might belong 
there, but only 'partial' is in
the proposal.

Peter Harris