You may have to use the new yield from, available since Python 3.3, known as “delegated generator”. If I understood the question correctly, I came to the same issue, and found an answer elsewhere. I wanted to do something like this: def f(): def g(): do_something() yield x … yield y do_some_other_thing() yield a … … Read more
Upd: Starting with Python 3.6 we have asynchronous generators and able to use yield directly inside coroutines. import asyncio async def async_generator(): for i in range(3): await asyncio.sleep(1) yield i*i async def main(): async for i in async_generator(): print(i) loop = asyncio.get_event_loop() try: loop.run_until_complete(main()) finally: loop.run_until_complete(loop.shutdown_asyncgens()) # see: https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.shutdown_asyncgens loop.close() Old answer for Python 3.5: … Read more
def generate_nothing(): return yield
If you don’t use the results of your yields,* you can always turn this: yield from foo … into this: for bar in foo: yield bar There might be a performance cost,** but there is never a semantic difference. Are the entries from the two halves (upper and lower) appended to each other in one … Read more
Note: this was a bug in the CPython’s handling of yield in comprehensions and generator expressions, fixed in Python 3.8, with a deprecation warning in Python 3.7. See the Python bug report and the What’s New entries for Python 3.7 and Python 3.8. Generator expressions, and set and dict comprehensions are compiled to (generator) function … Read more
I think the first one is actually a syntactic sugar of the other. In other words there is no behavioural difference. What the second form allows though is to “save” the block in a variable. Then the block can be called at some other point in time – callback. Ok. This time I went and … Read more
Using yield turns a function into a generator. A generator is a specialized type of iterator. for always loops over iterables, taking each element in turn and assigning it to the name(s) you listed. spinning_cursor() returns a generator, the code inside spinning_cursor() doesn’t actually run until you start iterating over the generator. Iterating over a … Read more
Eric Lippert recently wrote a series of blog posts about why yield is not allowed in some cases. Part 1 Part 2 Part 3 Part 4 Part 5 Part 6 EDIT2: Part 7 (this one was posted later and specifically addresses this question) You will probably find the answer there… EDIT1: this is explained in … Read more
There are only slight differences in the two. You can use the dis module to examine this sort of thing for yourself. Edit: My first version decompiled the generator expression created at module-scope in the interactive prompt. That’s slightly different from the OP’s version with it used inside a function. I’ve modified this to match … Read more
Yes, it’ still a generator. The return is (almost) equivalent to raising StopIteration. PEP 255 spells it out: Specification: Return A generator function can also contain return statements of the form: “return” Note that an expression_list is not allowed on return statements in the body of a generator (although, of course, they may appear in … Read more