En Wed, 07 May 2008 18:38:15 -0300, globalrev <[EMAIL PROTECTED]>
escribió:
i have a rough understanding of lambda but so far only have found use
for it once(in tkinter when passing lambda as an argument i could
circumvent some tricky stuff).
what is the point of the following function?
def addn(n):
return lambda x,inc=n: x+inc
lambda is just a shortcut for defining a function without a name.
The above code is the same as:
def addn(n):
def inner(x, inc=n):
return x+inc
return inner
It should be clear now that addn returns a function. addn is a "function
factory": builds functions by request. You ask it "give me a function that
adds 5" and addn returns that function.
if i do addn(5) it returns
addn(5)
<function <lambda> at 0x01D81830>
If you try the other version, you would get:
<function inner at 0x00A3B970>
It's the same thing, except that lambda has no name.
ok? so what do i write to make it actually do something.
adder5 = addn(5)
adder5(3)
-> 8
and is the
inc=n necessary i cant do x+n?
Yes, you can, but there is a subtle difference that's hard to explain, and
in this case it's absolutely irrelevant. Using inc=n "does the right
thing" as it's a bit more efficient too.
--
Gabriel Genellina
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