Make TypedResource covariant in A

[iphydf]

Just like one can implicitly convert a ViewGroup to a View, we should be able to pass a TypedResource[ViewGroup] as TypedResource[View].

Workaround:

object TRUtil {
  def convert[A1, A2 <: A1](tr: TypedResource[A2]): TypedResource[A1] = {
    TypedResource[A1](tr.id)
  }
}

[pfn]

What is the use-case?

On Wed, Oct 5, 2016 at 8:42 AM iphydf [email protected] wrote:

Just like one can implicitly convert a ViewGroup to a View, we should be
able to pass a TypedResource[ViewGroup] as TypedResource[View].

Workaround:

object TRUtil {
def convert[A1, A2 <: A1](tr: TypedResource[A2]): TypedResource[A1] = {
TypedResourceA1
}
}

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[iphydf]

The use case is no longer there. I used to pass TypedResource around, but in my case I could actually just pass the View around. In general, what is the harm in adding covariance?

[pfn]

I'd rather have a compelling reason to add covariance rather than vice versa

[chenakam]

I think add "+" to TypedResource[A] means TypedResource[+A] is faultless. No logical problems will triggered. TypedViewHolder[+T <: View] the same way.