This only works in Python 3.2+: >>> def gen(): yield 0; yield 1 … >>> a = gen() >>> import inspect >>> inspect.getgeneratorstate(a) ‘GEN_CREATED’ >>> next(a) 0 >>> inspect.getgeneratorstate(a) ‘GEN_SUSPENDED’ >>> next(a) 1 >>> inspect.getgeneratorstate(a) ‘GEN_SUSPENDED’ >>> next(a) Traceback (most recent call last): File “<stdin>”, line 1, in <module> StopIteration >>> inspect.getgeneratorstate(a) ‘GEN_CLOSED’ So, the … Read more
Ruby’s yield is not an iterator like in C# and Python. yield itself is actually a really simple concept once you understand how blocks work in Ruby. Yes, blocks are a functional programming feature, even though Ruby is not properly a functional language. In fact, Ruby uses the method lambda to create block objects, which … Read more
yield expression returns control to the whatever is using the generator. The generator pauses at this point, which means that the @contextmanager decorator knows that the code is done with the setup part. In other words, everything you want to do in the context manager __enter__ phase has to take place before the yield. Once … Read more
Iterators do not work recursively like that. You have to re-yield each result, by replacing explore(path) with something like for value in explore(path): yield value Python 3.3 added the syntax yield from X, as proposed in PEP 380, to serve this purpose. With it you can do this instead: yield from explore(path) If you’re using … Read more
time.sleep(0) is sufficient to yield control — no need to use a positive epsilon. Indeed, time.sleep(0) MEANS “yield to whatever other thread may be ready”.
No, there isn’t I’m afraid. F# does support this with yield!, but there’s no equivalent in C# – you have to use the loop, basically. Sorry… I feel your pain. I mentioned it in one of my Edulinq blog posts, where it would have made things simpler. Note that using yield return recursively can be … Read more
a is a generator object. The first time you call next on it, the body is evaluated up to the first yield expression (that is, the first to be evaluated: the inner one). That yield produces the value 1 for next to return, then blocks until the next entry into the generator. That is produced … Read more
Since this question doesn’t specify; I’ll provide an answer that applies in Python >= 3.3 If you need only to return that list, do as Anurag suggests, but if for some reason the function in question really needs to be a generator, you can delegate to another generator; suppose you want to suffix the result … Read more
You can use content_for? to check if there is content with a specific name: <% if content_for?(:page_title) %> <%= yield(:page_title) %> <% else %> <%= default_page_title %> <% end %> or <%= content_for?(:page_title) ? yield(:page_title) : default_page_title %> Then in your views you can specify the content like <% content_for :page_title do %> Awesome page … Read more
You can also send values to generators. If no value is sent then x is None, otherwise x takes on the sent value. Here is some info: http://docs.python.org/whatsnew/2.5.html#pep-342-new-generator-features >>> def whizbang(): for i in range(10): x = yield i print ‘got sent:’, x >>> i = whizbang() >>> next(i) 0 >>> next(i) got sent: None … Read more