You bring up a criticism that has been raised before1. The cleanup in this case is non-deterministic, but it will happen with CPython when the generator gets garbage collected. Your mileage may vary for other python implementations… Here’s a quick example: from __future__ import print_function import contextlib @contextlib.contextmanager def manager(): “””Easiest way to get a … Read more
We talked about this in the TC39 face-to-face meetings and it is deliberate that we don’t expose a way to detect whether a function is a generator or not. The reason is that any function can return an iterable object so it does not matter if it is a function or a generator function. var … Read more
Q&A How can I use it? With arrow labels when a full block is needed: int value = switch (greeting) { case “hi” -> { System.out.println(“I am not just yielding!”); yield 1; } case “hello” -> { System.out.println(“Me too.”); yield 2; } default -> { System.out.println(“OK”); yield -1; } }; With traditional blocks: int value … Read more
Note: This question (and the original part of my answer to it) are only really meaningful for Python versions prior to 3.7. The behavior that was asked about no longer happens in 3.7 and later, thanks to changes described in PEP 479. So this question and the original answer are only really useful as historical … Read more
You can think of yield() as “return, and next time start from where you stopped“: val sequence = sequence { val start = 0 yield(start) // first return yieldAll(1..5 step 2) // if called again, will start from here yieldAll(generateSequence(8) { it * 3 }) // if called more that six times, start from here … Read more
Take a look at boost::Coroutine. It does what you want. http://www.crystalclearsoftware.com/soc/coroutine/index.html#coroutine.intro Example from tutorial http://www.crystalclearsoftware.com/soc/coroutine/coroutine/tutorial.html int range_generator(generator_type::self& self, int min, int max) { while(min < max) self.yield(min++); self.exit(); }
I. Alternatives Foreword: I will use a much simpler generator, because the problem does not concern the generator complexity but rather the signals between the generator and consumer, and the call of the consumer itself. This simple generator just generates the integer numbers from 0 to 9. 1. With a function value A generate-consumer pattern … Read more
You can only use yield return in a function that returns an IEnumerable or an IEnumerator, not a List<T>. You need to change your function to return an IEnumerable<DesktopComputer>. Alternatively, you can rewrite the function to use List<T>.ConvertAll: return GetComputerIdTags().ConvertAll(pcTag => new DesktopComputer() { AssetTag = pcTag, Description = “PC ” + pcTag, AcquireDate = … Read more
You can’t pass multiple blocks, per se, but you can pass multiple procs or lambdas: Using 1.9 syntax: opportunity ->{ @some_array.empty? }, ->{ @some_other_array.empty? } and in the method itself: def opportunity(lambda1, lambda2) if lambda1.() @opportunities += 1 end if lambda2.() @performances += 1 end end
yield is best used when you have a function that returns a sequence and you want to iterate over that sequence, but you do not need to have every value in memory at once. For example, I have a python script that parses a large list of CSV files, and I want to return each … Read more