[英]Why implicit class in Scala must reside in another trait/class/object?
Based on the scala documentation: http://docs.scala-lang.org/overviews/core/implicit-classes.html , the implicit class has three restrictions, and the very first one, I quote here, is 基于scala文档: http : //docs.scala-lang.org/overviews/core/implicit-classes.html ,隐式类有三个限制,我在这里引用的第一个是
They must be defined inside another trait/class/object 它们必须在另一个trait / class / object中定义
What is the intuition/reason to explain/justify such a restriction? 解释/证明这种限制的直觉/理由是什么?
An implicit class decomposes into a "normal" class and an implicit method that instantiates the class: 隐式类分解为“普通”类和实例化类的隐式方法:
implicit class IntOps(i: Int) { def squared = i * i }
Is rewritten as 被重写为
class IntOps(i: Int) { def squared = i * i }
implicit def IntOps(i: Int) = new IntOps(i)
But in Scala, you cannot define a method ( def IntOps
) outside of an object or a class. 但是在Scala中,您无法在对象或类之外定义方法( def IntOps
)。 That is why. 这就是为什么。
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