Question

Simple question, I have code like this:

class Context[A] {
    def t: A
}

object Context {
    implicit object StandardContext extends Context[SomeObject] {
        def t = SomeObject
    }
}

SomeObject is an object that holds values and functions that I would like to access in my Context. Unfortunately the different types for A I would like to include do not have a common parent class, other than java.lang.Object.

SomeObject is defined like this:

final object SomeObject {
    def func1 = ...
    def func2 = ...
}

In some code that’s not mine. But the Scala compiler complains SomeObject is not a value when I try the thing above. As far as I know it, an object in scala is a singleton class, so it would be a type, yes, but also a value, the only value of its own type.

What I wanna do is stuff like this:

class Foo[A](bar: Int)(implicit context: Context[A]) {
    def baz = context.t.baz
}

Anyone can tell me how to solve this or have a better idea of solving it?

Answer 1

implicit object StandardContext extends Context[SomeObject] {
    def t = SomeObject

The first SomeObject is a type, a type-parameter for Context, but in the second row it is used as if it were a variable.

Think of

 ... List [Int] {
     def x = Int // fail

Int is a type, not a variable, so x can’t return Int, it could only return an integer.