Values yielded by imap inconsistent with map

[spyoungtech]

Currently, imap will not yield values returned by the exception handler and will not yield None values. However, responses from map will include values returned by the exception handler and will include None values.

Is there any reason why imap shouldn't be consistent with map in this way, at least for the exception handler?

Forgive me if I'm missing something, but I would have thought something like this would be appropriate.

    for request in pool.imap_unordered(send, requests):
        if request.response is not None:
            yield request.response
        elif exception_handler:
            yield exception_handler(request, request.exception)
        else: # probably leave this clause out
            yield None

In other words, a and b should be the same in this example.

import grequests

req_list = [grequests.get('http://fakedomain')]

def ex_handler(req, ex):
    return "foo"

a = grequests.map(req_list, exception_handler=ex_handler)
b = [item for item in grequests.imap(req_list, exception_handler=ex_handler)]

But they are not

>>> a = grequests.map(req_list, exception_handler=ex_handler)
>>> b = [item for item in grequests.imap(req_list, exception_handler=ex_handler)]
>>> a
['foo']
>>> b
[]

[Raytlty]

Yeah, I have notice that. I don't think exception_handler for all responses is a good option as well.

[spyoungtech]

There may very well be a good reason for it, but if there is, it's not immediately apparent to me. The current logic for map is this

    for request in requests:
        if request.response is not None:
            ret.append(request.response)
        elif exception_handler and hasattr(request, 'exception'):
            ret.append(exception_handler(request, request.exception))
        else:
            ret.append(None)

So why not the same for imap? Its counterpart logic doesn't yield the exception results. Not clear to me why this is.

    for request in pool.imap_unordered(send, requests):
        if request.response is not None:
            yield request.response
        elif exception_handler:
            exception_handler(request, request.exception) # why not yield this?

If no behavior change is warranted, perhaps some documentation on this behavior. The way the readme is worded right now had given me the impression that the results for map and imap would be identical, just unordered.

In my situation, I had worked out a solution to a problem using map (but cautiously not relying on order) where the exception_handler would produce a useful value. To my surprise, when switching to imap, it didn't produce the same values :(

[spyoungtech]

addressed in #126