Python 3中词典生成器的文档在哪里？

Question

I mean this:

>>> d = {a : a ** 2 for a in range(7)}
>>> d
{0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36}

I managed to find these resources:

• http://docs.python.org/py3k/tutorial/datastructures.html?highlight=dict%20comprehension
• http://www.python.org/dev/peps/pep-0274/

These seem to be just tutorials; I want to find it in the documentation itself.

Answer 1

You are looking for the "Displays for lists, sets and dictionaries" section of the expressions chapter of the reference documentation.

That section deals with both defining literal lists, sets and dictionaries, as well as comprehension expressions for those types.

For constructing a list, a set or a dictionary Python provides special syntax called “displays”, each of them in two flavors:

• either the container contents are listed explicitly, or
• they are computed via a set of looping and filtering instructions, called a comprehension.