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目录 生成器 一、yield关键字 二 、 协同程序 生成器 一、yield关键字 yield的英文单词意识就是生产，在函数中但凡出现yield关键字，在调用函数，就不会继续执行函数体代码，而是会返回一个值。 def func(): print(1) yield print(2) yield g = func() print(g) #输出：# generator 生成器 <generator object func at 0x0000019C5C5BD448> 生成器 的本质就是迭代器，同时也并不仅仅是迭代器，不过迭代器之外的用途实在是不多，所以我们可以认为：生成器提供了非常方便的自定义迭代器的途径。并且从python2.5+开始，[PEP 342:通过增强生成器实现协同程序的实现位生成器加入了更多的特性，这意味着，生成器还可以完成更多的工作。这部分我们会在稍后的部分介绍。 def func(): print('from func 1') yield 'a' print('from func 2') yield 'b' g = func() print(g.__iter__()) print(g.__iter__()==g) res1 = g.__next__() print(res1) res2 = next(g) print(res2) #输出： <generator

三元表达式/列表推导式/字典生成式 只是让你的代码少一些，但是逻辑没发生变化 三元表达式 # 三元表达式只支持双分支结构 name = 'apple' print('red') if name == 'apple' else print('blue') red 列表推导式 lt = [i ** 2 for i in range(10)] print(lt) [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] 字典生成式 # 字典生成式一般与zip连用 z = zip(['a','b','c','d'],[1,2,3,4]) #压缩方法，Python解释器的内置方法 dic = {k:v**2 for k,v in z} print(dic) {'a': 1, 'b': 4, 'c': 9, 'd': 16 生成器 #生成器：自定义迭代器，生成器就是迭代器(自己造出来的) #yield关键字的三个特性 #1.yield可以把函数变成生成器（自定制的迭代器对象，具有__iter__和__next__方法） #2.yield可以停止函数，再下一次next再次运行yield下面的代码 #3.有n个yield生成器就有n个元素，就可以next n次，第n+1次next会报错 # 自定义一个range()函数 def range(x,y,z): #普通版 while x

I have seen this syntax in MSDN: yield break , but I don't know what it does. Does anyone know? Damir Zekić It specifies that an iterator has come to an end. You can think of yield break as a return statement which does not return a value. For example, if you define a function as an iterator, the body of the function may look like this: for (int i = 0; i < 5; i++) { yield return i; } Console.Out.WriteLine("You will see me"); Note that after the loop has completed all its cycles, the last line gets executed and you will see the message in your console app. Or like this with yield break : int i

def range(*args,step= 1): args = list(args) if len(args) == 2: yield args[0] while args[0]<args[1]-1: args[0] +=step yield args[0] elif len(args) == 1: count = 0 yield count while count < args[0]-1: count += 1 yield count for i in range(10): print(i) C:\Users\Administrator\AppData\Local\Programs\Python\Python36\python.exe "D:/python/8.9/03 字典生成式.py" 0 1 2 3 4 5 6 7 8 9 来源： https://www.cnblogs.com/oxtime/p/11348150.html

yield的英文单词意思是生产，在函数中但凡出现yield关键字，再调用函数，就不会继续执行函数体代码，而是会返回一个值。 52生成器-停止.jpg?x-oss-process=style/watermark def func(): print(1) yield print(2) yield g = func() print(g) <generator object func at 0x10ddb6b48> 生成器的本质就是迭代器，同时也并不仅仅是迭代器，不过迭代器之外的用途实在是不多，所以我们可以大声地说：生成器提供了非常方便的自定义迭代器的途径。并且从Python 2.5+开始，[PEP 342：通过增强生成器实现协同程序]的实现为生成器加入了更多的特性，这意味着生成器还可以完成更多的工作。这部分我们会在稍后的部分介绍。 def func(): print('from func 1') yield 'a' print('from func 2') yield 'b' g = func() print(F"g.__iter__ == g: {g.__iter__() == g}") res1 = g.__next__() print(f"res1: {res1}") res2 = next(g) print(f"res2: {res2}") next(g) #

I played with generators in Nodejs v0.11.2 and I'm wondering how I can check that argument to my function is generator function. I found this way typeof f === 'function' && Object.getPrototypeOf(f) !== Object.getPrototypeOf(Function) but I'm not sure if this is good (and working in future) way. What is your opinion about this issue? Erik Arvidsson 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

Is it feasible to use the yield keyword to implement a simple state machine as shown here . To me it looks like the C# compiler has done the hard work for you as it internally implements a state machine to make the yield statement work. Can you piggy-back on top of the work the compiler is already doing and get it to implement most of the state machine for you? Has anyone done this, is it technically possible? It's feasible but it is a bad idea. Iterator blocks were created to help you write custom iterators for collections, not for solving the general-purpose problem of implementing state

I have the following function to get validation errors for a card. My question relates to dealing with GetErrors. Both methods have the same return type IEnumerable<ErrorInfo> . private static IEnumerable<ErrorInfo> GetErrors(Card card) { var errors = GetMoreErrors(card); foreach (var e in errors) yield return e; // further yield returns for more validation errors } Is it possible to return all the errors in GetMoreErrors without having to enumerate through them? Thinking about it this is probably a stupid question, but I want to make sure I'm not going wrong. It's definitely not a stupid