Accessing type-member in Scala

Question

I have a toy class with type member T.

class A { type T = Int }

How can I access my type member. e.g. get the type or modify it.

val a = new A
a.T = String //error: value T is not a member of A

Since T is my member , why I can not access it?

score 4 · Accepted Answer · edited May 23 '17 at 11:33

4

Type members are more like generic parameters than regular class members. Like a generic parameter, you cannot reassign a type parameter or access it from an instance of the class. Read more about type members here, and the difference between abstract types and generic parameters here.

edited May 23 '17 at 11:33

Community

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answered Mar 26 '15 at 02:25

Ben Reich

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In the OP's case it isn't abstract, it's fixed to `Int`. It's just that type members cannot be accessed or reassigned like values. – Michael Zajac Mar 26 '15 at 02:44

score 3 · Answer 2 · answered May 25 '16 at 02:08

3

You can't access it as a value, but you can access it as a type:

scala> class A { type T = Int }
scala> val a = new A
scala> val someInt: a.T = 5
someInt: a.T = 5

answered May 25 '16 at 02:08

abc123

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Accessing type-member in Scala

2 Answers2