Why can't Delphi infer the type for the TEnumerable <T> parameter?

Question

Consider the following utility class declaration in Delphi 2010:

TEnumerableUtils = class
public
  class function InferenceTest<T>(Param: T): T;
  class function Count<T>(Enumerable: TEnumerable<T>): Integer; overload;
  class function Count<T>(Enumerable: TEnumerable<T>; Filter: TPredicate<T>): Integer; overload;
end;

Somehow the output about the compiler seems to have problems:

var
  I: Integer;
  L: TList<Integer>;
begin
  TEnumerableUtils.InferenceTest(I);  // no problem here
  TEnumerableUtils.Count(L);          // does not compile: E2250 There is no overloaded version of 'Count' that can be called with these arguments
  TEnumerableUtils.Count<Integer>(L); // compiles fine
end;

The first call works as expected, and T is correctly output as Integer.

The second call does not work, if I have not added <Integer> yet , then it works, as can be seen from the third call. Am I doing something wrong or is it type inference in Delphi that just doesn't support it (I don't think this is a problem in Java, so I expected it to work in Delphi as well).

Answer 1

, ; . - , , .

, ( T, ). , T. -, , TList<T> generic; T type Integer TList<T>.