Base types

New features since Delphi 7 > Generics > Base types

The base type of a parameterized class or interface type might be an actual type or a constructed type

 type

    TFoo1<T> = class(TBar)            // Actual type

    end;

    TFoo2<T> =  class(TBar2<T>)       // Open constructed type

    end;

    TFoo3<T> = class(TBar3<Integer>)  // Closed constructed type

    end;

->

// Actual type

public class TFoo1<T> : TBar

{

  public TFoo1() {}

};       

// Open constructed type

public class TFoo2<T> : TBar2<T>

{

  public TFoo2() {}

};  

// Closed constructed type

public class TFoo3<T> : TBar2<int>

{

  public TFoo3() {}

};

Class, interface, record, and array types can be declared with type parameters.

type

   TRecord<T> = record

     FData: T;

   end;

 type

   IAncestor<T> = interface

     function GetRecord: TRecord<T>;

   end;

   IFoo<T> = interface(IAncestor<T>)

     procedure AMethod(Param: T);

   end;

 type

   TFoo<T> = class(TObject, IFoo<T>)

     FField: TRecord<T>;

     procedure AMethod(Param: T);

     function GetRecord: TRecord<T>;

   end;

->

public struct TRecord<T>

{

  public T FData;

  public static TRecord<T> CreateRecord(){return new TRecord<T>();}

};

public interface IAncestor<T> : IInterface

{

  TRecord<T> GetRecord();

};

public interface IFoo<T> : IAncestor<T>

{

  void AMethod(T Param);

};

public class TFoo<T> : TObject, IFoo<T>

{

  public TRecord<T> FField = TRecord<T>.CreateRecord();

  public void AMethod(T Param){...}

  public TRecord<T> GetRecord(){...}

  public TFoo() {}

};

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