什么是“发电机对象"?在django? [英] What is "generator object" in django?

问题描述

我正在使用Django投票程序包，当我在外壳中使用方法get_top()时，它返回类似生成器对象位于0x022f7AD0 之类的内容，我以前从未见过类似的东西，怎么办您访问它是什么?

Am using Django voting package and when i use the method get_top() in the shell, it returns something like "generator object at 0x022f7AD0, i've never seen anything like this before, how do you access it and what is it?

我的代码:

v=Vote.objects.get_top(myModel, limit=10, reversed=False)
print v
<generator object at 0x022f7AD0>

注意:我以为 get_top 会返回一个很好的myModel列表，我可以执行 v.name 等

NB: I thought get_top will just return a nice list of myModel, which i can do something like v.name etc

推荐答案

如果需要列表，只需在生成器对象上调用list().

If you want a list, just call list() on your generator object.

python中的生成器对象有点像惰性列表.仅当您遍历元素时才对它们进行评估. (因此，呼叫清单将对所有呼叫者进行评估.)

A generator object in python is something like a lazy list. The elements are only evaluated as soon as you iterate over them. (Thus calling list on it evaluates all of them.)

例如，您可以这样做:

>>> def f(x):
...  print "yay!"
...  return 2 * x
>>> g = (f(i) for i in xrange(3))    # generator comprehension syntax
>>> g
<generator object <genexpr> at 0x37b6c0>

>>> for j in g: print j
... 
yay!
0
yay!
2
yay!
4

仅在迭代f时查看如何评估f.您可以在此处找到有关该主题的出色材料: http://www.dabeaz.com/generators/

See how f is evaluated only as you iterate over it. You can find excellent material on the topic here: http://www.dabeaz.com/generators/

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