[fpc-pascal] private type and type compatibility

[Xiangrong Fang]

Hi All,

I have the following class:

type
  generic TVector<T> = class
  private type
    TDataType = array of T;
  private
    FData: TDataType;
    ... ...
  public
    ... ...
    function Slice(APos: Integer = -1; ACount: Integer = -1): TDataType;
  end;

The Slice() method return a portion of the data as a dynamic array.

My question is, as I define TDataType as PRIVATE type, why it is still
usable outside of the class?  In the main program I did:

type
  TIntVector = specialize TVector<Integer>;
var
  iv: TIntVector;
  ia: array of Integer;
begin
  iv := TIntVector.Create;
  ... ...
  ia := iv.Slice;
end.

This will assign a TDataType (is it TVector$TDataType or
TIntVector$TDataType? I don't know) to an "array of Integer". Why this
assignment works?

i.e. how does the type system work?!

Best Regards,
Xiangrong
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