如何通过 Scala 反射获得可用的隐式? [英] How to get implicits available via Scala reflection?

问题描述

我正在编写一个解析器生成器来创建 Scala 案例类.举个例子:

I'm writing a parser-generator that creates Scala case classes. Take this example:

case class Foo(
   name : String,
   age : Int
)(implicit other:Int){}

当我想实现一个 Foo 实例时，我的解析器生成器知道所有 3 个成员，包括隐含的其他".我有数据来填充 name &年龄.

When I want to materialize a Foo instance my parser-generator has knowledge of all 3 members, including the implicit 'other'. I have the data to populate name & age.

使用 Scala 反射，如何在创建对象时检查隐式环境"以找到合适的其他"值?

Using Scala reflection, how can I inspect the "implicit environment" when the object will be created to find an appropriate value for 'other'?

推荐答案

您不能:可用的隐式依赖于导入、局部变量等，而这些在运行时根本不可用.如果您可以使用宏，则可以使用 c.inferImplicitValue 方法.请参阅 Scala 宏 - 使用 `c.prefix` 推断隐式值 或 https://groups.google.com/forum/#!topic/scala-language/rqNZMBuJLtE 一些例子，但如果你需要这条路线的帮助，我建议提出一个单独的问题.

You can't: the implicits available depend on things like imports, local variables, etc. which aren't available at runtime at all. If you can get away with a macro, there is the c.inferImplicitValue method. See Scala macro - Infer implicit value using `c.prefix` or https://groups.google.com/forum/#!topic/scala-language/rqNZMBuJLtE for some examples, but if you want help with this route I advise asking a separate question.

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