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42 lines
No EOL
974 B
Markdown
42 lines
No EOL
974 B
Markdown
# 传播赋值
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在分解赋值中，将 `...` 放在变量前面会将所有剩余元素展开到该变量中。 这称为扩展赋值。
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```python
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[x,...y] = [1, 2, 3]
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assert x == 1
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assert y == [2, 3]
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x, ...y = (1, 2, 3)
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assert x == 1
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assert y == (2, 3)
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```
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## 提取赋值
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如果在 `...` 之后没有写入任何内容，则忽略并分配剩余的元素。 这种类型的扩展赋值具体称为抽取赋值。
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提取分配是一种方便的语法，用于本地化模块或记录中的特定属性。
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```python
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{sin; cos; tan; ..} = import "math"
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```
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After that, you can use `sin, cos, tan` locally.
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You can do the same with records.
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```python
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record = {x = 1; y = 2}
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{x; y; ...} = record
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```
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If you want to expand all, use `{*} = record`. It is `open` in OCaml.
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```python
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record = {x = 1; y = 2}
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{*} = records
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assert x == 1 and y == 2
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```
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<p align='center'>
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<a href='./27_comprehension.md'>上一页</a> | <a href='./29_decorator.md'>下一页</a>
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</p> |