Op 20-11-15 om 08:49 schreef dieter:
> In addition, the last few days have had two discussions in this list
> demonstrating the conceptial difficulties of late binding -- one of them:
>
> Why does "[lambda x: i * x for i in range(4)]" gives
> a list of essentially the same functions?
Can you (or someone else) explain what a list comprehension is equivallent of.
Especially in python3.
Take this simple list comprhesion:
[x * x for x in range(10)]
what would this be equivallent of? Something like:
def lch1():
ls = []
for x in range(10):
ls.append(x * x)
return ls
Or more something like:
def lch2():
def expr(x):
return x * x
ls = []
for x in range(10):
ls.append(expr(x))
return ls
For this example it doesn't make a difference but for the example above
it would become important.
def lch3():
ls = []
for i in range(4):
ls.append(lambda x: i * x)
return ls
versus
def lch4():
def expr(i):
return lambda x: i * x
ls = []
for i in range(4)
ls.append(expr(i))
return ls
Now from the result we get I expect list comprehensions to work more
like lch1 and lch3 rather than lch2 and lch4. But I can understand
people who think of the expression as a function of the variable that
is iterated over.
Am I missing something? Would it be worthwile considering changing
this behaviour?
--
Antoon.
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