问题标签 [scala-2.12]
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scala - Scala - 覆盖抽象方法的类型类
我在 scala 2.12 上有点挣扎:
我有以下层次结构:
效果很好。但我想为 writer 提供一个替代实现:
但我明白了object creation impossible, since method write in trait Writer of type (config: Playground.A)Unit is not defined
我假设由于 B 是 A,这应该有效。如何使用wherewrite
类型的配置覆盖B
B <: A
斯卡斯蒂:https ://scastie.scala-lang.org/QBaiiDP4Sj2lptUjrWLJYw
编辑: - - - - - - - - - - - - - - - - - - - - - - - - ------------
根据一些输入,我将实现更改为:
哪个有效。
但是,如果我修改它以访问 中的变量config
,它会中断:
和value format is not a member of type parameter B
https://scastie.scala-lang.org/Xj2rKbbiTmG7raZgQZYfHA
欣赏输入。