[英]pack/unpack a generator
I have a two generators.我有两个发电机。 First generator sometimes needs to call second generator and yield back values it got from there:
第一个生成器有时需要调用第二个生成器并返回它从那里获得的值:
def a():
for _b in b():
yield _b
def b():
yield 1
yield 2
for _a in a():
print _a
Is there a more elegant way to do this:有没有更优雅的方法来做到这一点:
for _b in b():
yield _b
I've tried this:我试过这个:
yield *b()
But surely it doesn't work.但肯定是行不通的。 I have Python 2.6.
我有 Python 2.6。
I think you mean PEP380 .我想你的意思是PEP380 。 It's available from Python 3.3 .
它可从 Python 3.3 获得。 It looks like:
看起来像:
yield from b()
There is no special syntax for that in Python2.在 Python2 中没有特殊的语法。 You just use a for-loop.
您只需使用 for 循环。
The a
function in your question is actually completely useless.您问题中
a
function 实际上完全没用。 You can just use b
in it's place.你可以在它的地方使用
b
。
You can use a generator expression.您可以使用生成器表达式。 It's about as concise as the loop, plus it indicates that your code is primarily for producing a return value instead of a side effect.
它与循环一样简洁,而且它表明您的代码主要用于产生返回值而不是副作用。
def a():
return (_b for _b in b())
As phihag said, you can probably simply write a = b
if your code is really like this example, since a and b return the same sequence.正如 phihag 所说,如果你的代码真的像这个例子,你可能可以简单地写
a = b
,因为 a 和 b 返回相同的序列。
Well, in this simple example, you could just write a = b
or a = lambda: b
.好吧,在这个简单的例子中,你可以只写
a = b
或a = lambda: b
。 But if a
adds elements of its own, you can use itertools.chain :但是如果
a
添加了它自己的元素,你可以使用itertools.chain :
import itertools
def a():
return itertools.chain(['a-value'], b())
Bear in mind that although this variant may be shorter, for: yield
is a quite intuitive (and therefore easy to understand) pattern.请记住,尽管此变体可能更短,但
for: yield
是一种非常直观(因此易于理解)的模式。
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