类型会实现 From
和 Into
以加快类型转换:
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实现 From
后,系统会自动实现 Into
:
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Speaker Notes
This slide should take about 10 minutes.
- 这就是为什么通常只需实现
From
,因为您的类型也会实现 Into
。
- 若要声明某个函数实参输入类型(例如“任何可转换成
String
的类型”),规则便会相反,此时应使用 Into
。 您的函数会接受可实现 From
的类型,以及那些仅实现 Into
的类型。