annonymous functions -- how to

[Dave Benjamin]

Peter Hansen wrote:
> Dave Benjamin wrote:
> 
>> def add_thingy():
>>     def func(thingy_id):
>>         print 'got thingy id:', thingy_id
>>         def funnc(doodad_id):
>>             print 'got doodad id:', doodad_id
>>             def func(thingy_doodad):
>>                 print 'thingy doodad created, froobling...'
>>                 frooble(thingy_doodad)
>>                 print 'froobling complete'
>>             with_new_thingy_doodad(thingy_id, doodad_id, func)
>>         with_next_doodad_id(func)
>>     with_next_thingy_id(func)
>>
>> This function now has an infinite loop. Can you spot the reason?
> 
> Not offhand, and to be completely honest, the original with the longer 
> names was equally unreadable.  I doubt this is the best way to do 
> whatever the heck it is that this is supposed to do.

I agree. I think both are difficult to read. I find the first version 
that I originally posted (using an imaginary anonymous function syntax) 
much easier to understand.

I think I've made it pretty clear what this is supposed to do in my 
earlier post to Fredrik, delineating each step of the communication 
process. If you have a better way to do this, I'd certainly like to see it.

> Oh, and while I was typing my eyes fell on "funnc" misspelled above. 
> Presumably that's your loop...

Yes, precisely. And because of a typo, the wrong callback gets passed, 
causing it to use the same callback over and over. With anonymous 
functions, there would be nothing to name, and therefore, nothing to 
misspell.

> Spelling "func" as "_" would tend to avoid this as well, unless you have 
> a keyboard that repeats keys accidentally.

Hrmmm. Well, it is less to type.

Dave