Python 不允许在解包时注释变量的类型

Question

PEP 526说如下:

Note that, although the syntax does allow tuple packing, it does not allow one to annotate the types of variables when tuple unpacking is used.

为什么python在解包时不支持变量的类型注释？
附注。我必须先对类型进行注释，然后再进行解包，这很好，只是在解包时进行注释会更整洁。

Answer 1

在 Rejected/Postponed Proposals section 中有一些关于此的信息。 PEP 526 的:

Allow type annotations for tuple unpacking: This causes ambiguity: it's not clear what this statement means:

x, y: T

Are x and y both of type T, or do we expect T to be a tuple type of two items that are distributed over x and y, or perhaps x has type Any and y has type T? (The latter is what this would mean if this occurred in a function signature.) Rather than leave the (human) reader guessing, we forbid this, at least for now.

该评论似乎表明，最终可能会提出一种更简单的语法，并且不容易被误解。现在，我们不得不分别注释元组的类型。