Re: Python becoming less Lisp-like

[Jeff Shannon]

Martin Franklin wrote:
Tim Daneliuk wrote:
Except that in this case, removal will also complicate code in some
cases.  Consider this fragment of Tkinter logic:
UI.CmdBtn.menu.add_command(label="MyLabel",
                            command=lambda cmd=cmdkey: 
CommandMenuSelection(cmd))

In this case you perhaps should try using a class like so:-
UI.CmdBtn.menu.add_command(label="MyLabel",
   command=CommandMenuSelectionCallback(cmdkey))
Where CommandMenuSelectionCallback is a class like so:
class CommandMenuSelectionCallback:
    def __init__(self, key):
        self.key = key
    def __call__(self):
        print self.key
One could equivalently define CommandMenuSelectionCallback as a 
function which creates and returns closures --

def CommandMenuSelectionCallback(key):
    def func():
        CommandMenuSelection(key)
    return func
This should have the same practical value as the callable class; in 
both cases you have a callable taking a single argument, which 
produces a callable taking no arguments.  Whether one prefers that the 
resulting callable object be a class instance or a closure (function) 
seems to me to be largely a matter of taste.

Also, once Python 2.5 is realeased, one should be able to use the 
partial() function (see http://www.python.org/peps/pep-0309.html) to 
accomplish much the same thing in a more general fashion.  ISTM that 
partial() will cover somewhere between 50% and 95% of the current 
(reasonable) uses of lambda -- my guess being that it's towards the 
hight end of that range.

Jeff Shannon
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