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43 lines
1.3 KiB
Markdown
43 lines
1.3 KiB
Markdown
# 扩展语法
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[](https://gezf7g7pd5.execute-api.ap-northeast-1.amazonaws.com/default/source_up_to_date?owner=erg-lang&repos=erg&ref=main&path=doc/EN/syntax/30_spread_syntax.md&commit_hash=b80234b0663f57388f022b86f7c94a85b6250e9a)
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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。这称为展开赋值
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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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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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之后，您可以在本地使用`sin，cos，tan`
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您可以对记录执行相同的操作。
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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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如果要全部展开，请使用`{*}=record`。它在OCaml中是`open`。
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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='./28_comprehension.md'>上一页</a> | <a href='./30_decorator.md'>下一页</a>
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</p>
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