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crazy lambdas

Remco Gerlich scarblac at pino.selwerd.nl
Wed Feb 14 05:22:26 EST 2001 
Dan Parisien <dan at eevolved.com> wrote in comp.lang.python:
> e.callbacks.append(lambda d=dict, p=person: del d[p])
> 
> # .... later
> 
> e.trigger() #deletes
> ---
> those who use lambdas alot will notice my mistake. I, however, do not know 
> what I am doing wrong. I think it has something to do with the fact 'del 
> d[p]' doesn't have a value...

The problem is that it is a statement, not a function. Note that you don't
use parentheses after del either, just like with print, import, exec, etc.
Assignment isn't a function either.

> Is it possible to do what I want (make a custom one-time-use function that 
> is called much later and deletes a key from a dictionary)?

Make the function with a normal def. Make another function that creates
those functions so you don't have to do it all the time...

def make_deleter(dict, person):
   def deleter(dict=dict, person=person):
      del dict[person]
   return deleter
   
e.callbacks.append(make_deleter(dict, person))

-- 
Remco Gerlich
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