Interfaces/Generics

BIZ TMS Aurelius
1

Hi, Wagner
I'm try to implement Unit Test(DI, mocks, etc ), so i want to use interfaces. But interfaces 
cannot have generic methods, and we use a lot in Aurelius.

TUserX = class
private
  FName: String;
public
  property Name: String read FName write FName;
end; 

IDBBase = interface
    function Get(Id: integer; Detailed: Boolean): TUserX;
    function GetAll(Detailed: Boolean): TList<TUserX>;//Compiler don't support
end;

TDBCustomer = class(TInterfacedObject, IDBBase)
public
    function Get(Id: integer; Detailed: Boolean): TUserX;
    function GetAll(Detailed: Boolean): TList<TUserX>;
end;

i'm stuck, some suggestion?

Thank you very much.

2

That's a Delphi limitation unfortunately. Interfaces can't have generic methods, you can only have generic params in interface itself (e.g., IDBBase<T>).

Alternative is retrieve TObjectList or TList or create a type TUserXList and return it.
3

Hi,
 " Alternative is retrieve TObjectList or TList..."
how to do that?
function GetAll(Detailed: Boolean): TList;//?!
function GetAll(Detailed: Boolean): TObjectList;//?!

Thanks, Wagner

4

Yes, or TUserXList, it's your call, you will have to find the best solution that fits your needs to circumvent this limitation.

5

Sorry, Wagner
 But, i'm using like this: TList<TObject> or TList<TUserX> or TObjectList<UserX>.
 I don't understand what you meaning. Is there another way to use TList without generics?
 Can you detail a bit more?
Thanks a lot

6

TList and TObjectList are normal Delphi types that exist way before generics. You can learn how to use them. Alternatively, you can declare a fixed type like this:


TUserXList = TList<TUserX>;

and use TUserXList.
7

Hi, Wagner
  After add "Contnrs" in uses, i understand what you mean.

Thank you very much