Lambda alternative?

[Duncan Booth]

Paul Rubin <http://phr.cx@NOSPAM.invalid> wrote:

> Duncan Booth <duncan.booth at invalid.invalid> writes:
>> What exactly is your objection to using a named function here?...
>> Surely that would solve your pickle problem *and* give you more
>> meaningful tracebacks in your exceptions?
> 
> I don't think it would help the pickle problem.

Why wouldn't you think that?

class material(object):
    def __init__(self,density):
        self.density=density
        
def airdensity(T):
    	return 100000/(287*T)
air=material(airdensity)

steeldensity=lambda T:interp(T,[0,1000],[7856,7813])
steel=material(steeldensity)

from pickle import dumps, loads

dumped = dumps(air)
t = loads(dumped)
print t # works fine

dumped = dumps(steel) # pickle.PicklingError: Can't pickle <function 
# <lambda> at 0x0000000002C78A58>: it's not found as __main__.<lambda>