What is "lambda x=x : ... " ?

[Scott David Daniels]

zslevi at gmail.com wrote:
> I'm reading this page: http://www.ps.uni-sb.de/~duchier/python/continuations.html
> and I've found a strange usage of lambda:
> 
> ####################
> Now, CPS would transform the baz function above into:
> 
> def baz(x,y,c):
>         mul(2,x,lambda v,y=y,c=c: add(v,y,c))
> 
> ###################
> 
> What does "y=y" and "c=c" mean in the lambda function?
> I thought it bounds the outer variables, so I experimented a little
> bit:
> 
> #################
> x = 3
> y = lambda x=x : x+10
> 
> print y(2)
> ##################
> 
> It prints 12, so it doesn't bind the variable in the outer scope.
Primary use:


funcs = [lambda x=x: x+2 for x in range(10)]
print funcs[3]()

_or_

funcs = []
for x in range(10):
     funcs.append(lambda x=x: x+2)
print funcs[3]()


Try these w/o the default binding.

--Scott David Daniels
Scott.Daniels at Acm.Org