Types not added to binder on initial assignment

未关闭
#2,008 37 条评论 2 个 reaction 已指派 0 人 在 GitHub 查看

还没有人认领这个 Issue。

评估

难度
4/5
预计耗时
3-5 天
新手友好度
35/100
Issue 类型
缺陷
描述清晰度
基本清楚
活跃度
停滞
技术栈
python
领域
compilers

调研方向

Start by locating the binder handling for initial assignments and the existing Union/Optional tests mentioned in the issue. Check how annotated first assignments differ from later assignments. Done means the annotation is added to the binder on the initial assignment, the examples reveal the expected types, and affected tests are updated and passing.

由索引模型根据 Issue 内容生成。

描述

feature priority-2-low topic-strict-optional topic-union-types 
from typing import Union
x = 0  # type: Union[int, str]
reveal_type(x)  # Revealed type is 'Union[builtins.int, builtins.str]'
x = 0
reveal_type(x)  # Revealed type is 'builtins.int'

This means if you want to declare a union and then immediately use it as one specific member, you'll have an awkward time. For example:

x = "foo" # type: Optional[str]
x + "bar"  # E: Unsupported operand types for + ("Union[str, None]" and "str")

To be consistent with other assignments, we should add types to the binder on initial assignment. I think a number of Union/Optional tests depend on the current behavior, so those will need to be updated.

主要语言
Python
星标
20.6k
派生
3.3k
平均合并
1 天 18 小时
30 天内合并 PR
54

贡献指南

打开贡献指南

从这里开始

  1. 先读完整个 Issue，再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库，在一个分支上完成修改。
  4. 提交 Pull Request，并在描述里引用这个 Issue 编号。

python/mypy 的其他 Issue

查看 python/mypy 的全部 Issue

相似的 Issue

更多 Python Issue

把新 issue 发到你的邮箱

精选适合新手参与的 GitHub issue 摘要。