list of lambda

[Bengt Richter]

On 11 Nov 2005 18:28:22 -0800, Paul Rubin <http://phr.cx@NOSPAM.invalid> wrote:

>jena <jena at vlakosim.com> writes:
>> l=[lambda:x.upper() for x in ['a','b','c']]
>> then l[0]() returns 'C', i think, it should be 'A'
>
>Yeah, this is Python late binding, a standard thing to get confused
>over.  You want:
>
>  l = [lambda x=x: x.upper() for x in ['a', 'b', 'c']]

or if you want the upper() eagerly (and do it only once each,
in case of multiple lambda calls)

   l = [lambda x=x.upper():x for x in ['a', 'b', 'c']]

 >>> l = [lambda x=x.upper():x for x in ['a', 'b', 'c']]
 >>> for lamb in l: print lamb.func_defaults[0],'=?=',lamb()
 ...
 A =?= A
 B =?= B
 C =?= C

Regards,
Bengt Richter