[英]By-name type parameters
Imagine I have the following class definition: 想象一下,我有以下类定义:
class Foo[T]
and I want to do the following 我想做以下事情
def bar(x:Foo[ =>Int ]):Int = ???
But compiler fails with "no by-name parameter type allowed here" 但编译器失败,“此处不允许使用by-name参数类型”
How can I use a by-name type as type parameter for a generic method? 如何使用通配名类型作为通用方法的类型参数?
You'll have to provide your own lazy wrapper. 你必须提供自己的懒惰包装。 Something like this:
像这样的东西:
class Lazy[T](wrp: => T) {
lazy val value: T = wrp
}
and then: 然后:
def bar(x: Foo[Lazy[T]]): Int = ???
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