New CAT call

Revision as of 13:48, 27 October 2006 by Konradm (Talk | contribs) (→‎Detachable type)

Introduction

The ECMA standard introduces a new solution to the CAT call problem. Covariant redefinition of a formal argument is only possible to a detachable type: 

class A
feature
   f (a: ANY) do end
end
 
class B1
inherit A redefine f end
feature
   f (a: STRING) do end   -- not valid
end
 
class B2
inherit A redefine f end
feature
   f (a: ?STRING) do end   -- valid
end

This wiki discusses some of concerns related to this solution.

Detachable type

According to the new approach a detachable type can be attached to an object of "any" type.

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