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Jacek Laskowski

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Posts posted by Jacek Laskowski

  1. Posted

    15 hours ago, Stefan Glienke said:

    I meant the implementing class of the comparer or are you using the default from Generics.Defaults?

     

    Then just RegisterInstance(TEqualityComparer<whatever>.Default());

     

    Or make an overload without parameter where you create the default comparer and mark that one with [Inject] for the container to use that one because imo a comparer if it does not have dependencies itself falls into the category of a createable thus does not need to be injected.

     

    Ok, I paste more code with real example:

      

    program s4dgic;

uses
  System.Generics.Defaults,
  Spring.Collections,
  Spring.Container,
  System.SysUtils;

{$APPTYPE CONSOLE}
{$R *.res}

type
  TBaseClass<T, V> = class(TInterfacedObject)
  private
    fDict: IDictionary<T, V>;
  public
    constructor Create(const aComparer: IEqualityComparer<T>); virtual;
  end;

constructor TBaseClass<T, V>.Create(const aComparer: IEqualityComparer<T>);
begin
  inherited Create;
  fDict := TCollections.CreateDictionary<T, V>(aComparer);
end;

type
  RKey = record
    FieldA: Integer;
    FieldB: String;
  end;

  TMyEqualityComparer = class(TEqualityComparer<RKey>)
  public
    function Equals(const Left, Right: RKey): Boolean; override;
  end;

function TMyEqualityComparer.Equals(const Left, Right: RKey): Boolean;
begin
  Result := (Left.FieldA = Right.FieldA) and (Left.FieldB = Right.FieldB);
end;

type
  IMyIntf = interface ['{874B15D9-675E-428B-906A-D526FCC3AE0D}']
  end;

  TMainClass = class(TBaseClass<RKey, TObject>, IMyIntf)
  public
    constructor Create(const aComparer: IEqualityComparer<RKey>); override;
  end;

constructor TMainClass.Create(const aComparer: IEqualityComparer<RKey>);
begin
  inherited Create(aComparer);
end;

var
  C: TContainer;
  I : IMyIntf;
  
begin
  try
    C := TContainer.Create;

    >>>>>  how to register required types?   <<<<

    C.RegisterType<TMainClass>.Implements<IMyIntf>;
    C.Build;
    I := C.Resolve<IMyIntf>;
    C.Free;
    Readln;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;

end.

     

  2. Posted

    2 hours ago, Stefan Glienke said:

    Does the implementing class itself has dependencies the container should build? 

     

    Yes, I have class with IEqualityComparer<T> in constructor, so I need the container to be able to resolve this interface... but this is impossible?


      

    TMyClass<T> = class(TInterfacedObject, IMyInterface)
  constructor Create(const aKeyComparer : IEqualityComparer<T>);
end;

     

     

  8. Posted

    The class design is rather good, the override detection I need in order to optimize performance (class implements cache in the REST server).
    The ancestor (in base class) method returns always False, the descendant method can change this behavior, but if it does not change, I prefer to check the boolean flag rather than call the method (just because it's faster).

  10. Posted

    Such a simple example with inheritance:

      

    TAncestor = class
  procedure MethodX(); virtual
  procedure Do();
end;

TDescendantA = class(TAncestor) //override MethodX
  procedure MethodX(); override;
end;

TDescendantB = class(TAncestor) //no override MethodX
end;

procedure TAncestor.Do();
begin
 how to check if MethodX is overridden?  <<<<<<<<<<<<<<<<<<<<
end;

var
 A : TDescendatdA;
 B : TDescendantB;
begin
 A := TDescendatdA.Create;
 B := TDescendatdB.Create;
 A.Do();
 B.Do();

     

    How to check if MethodX is overridden?

     

  12. Posted

    23 hours ago, Primož Gabrijelčič said:

    Alternatives:

     

     

    from Microsft site:

     

    " [Network DDE is no longer supported. Nddeapi.dll is present on Windows Vista, but all function calls return NDDE_NOT_IMPLEMENTED.] "

    • Thanks 1

  16. Posted

    Yes, quality lies and cries. Recently, I have been working a little in VSCode and the node.js ecosystem. Environmental quality is ahead of Delphi for ages. In addition, it works steadily and quickly, although behind the scenes everything is based on slow JS!

    I have serious doubts that Delphi will ever catch up with the world in this area.

  24. Posted

    I register classes and factories in Spring:

      

    container.RegisterType<TMyClass>;
container.RegisterFactory<TMyClassFactory>;


    Then in the code I use:
      

     fClassFactory: TMyClassFactory;

[...]  
  
begin
  lMyClass: = fClassFactory();
  [some code]
  lMyClass.Free; <- who is responsible?
end;



    Who is responsible for the release of the object? Spring or me?

     

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