Delphi Test Assessment

Difficulty:

Easy

Q 1. Suppose, there is the next class hierarchy:

  TAncestor = class
     ...
     procedure SomeMethod; virtual;
     ...
  end;
  TInheritor = class (TAncestor)
    ...
     procedure SomeMethod; {directive}
    ... 
  end;

Specify the problems for these lines of code.
var
    Inheritor: TInheritor;
    Ancestor: TAncestor;
begin
    Inheritor := TInheritor(TAncestor.Create); {a}
    Inheritor.SomeMethod(); {b}
    Inheritor.Free;    
    
    Ancestor := TAncestor(TInheritor.Create); {c}
    Ancestor.SomeMethod(); {d}
    Ancestor.Free;
end;

Difficulty:

Easy

Q 2. Suppose, we have interface declaration, and classes declared as:

  ISomeInterface = interface(IInterface)
      ['{F4FAEE2B-FA98-4240-84FF-647725844C8F}']
      procedure SomeActivity;
  end;
  TImplementator = class(TInterfacedObject, ISomeInterface)
    procedure SomeActivity;
  end;

  TMaster = class
      private
        Obj: TImplementator;
      public
        constructor Create;
        function GetInterfacedObj: ISomeInterface;
  end;

with the follow implementation of TMaster:

constructor TMaster.Create;
begin
    Self.Obj := TImplementator.Create;
end;
function TMaster.GetInterfacedObj: ISomeInterface;
begin
    RESULT := Self.Obj;
end;

Which letters will contain the result of the Test() function call?

function Test: string;
    var Objt: TImplementator;
        Obji: ISomeInterface;
        Master: TMaster;
        ch: char;
        log: string;

    procedure Activity(Master: TMaster);
    begin
        Master.GetInterfacedObj.SomeActivity();
    end;
    
    begin
        log := '';
        try
            Master := TMaster.Create;
            try
                for ch := 'a' to 'b' do
                try
                    Activity(Master);
                except on E: Exception do
                    log := log + ch;
                end;
                try
                    
                except on E: Exception do
                    ShowMessage('');
                end;
            finally
                Master.Free;
            end;


            Objt := TImplementator.Create;
            try
                for ch := 'c' to 'd' do
                try
                    Obji := Objt;
                    Obji.SomeActivity();
                except on E: Exception do
                    log := log + ch;
                end;
            finally
                Objt.Free;
            end;
        except on E: Exception do
            log := log + 'e';
        end;
        RESULT := log;
end;

Note: There can be multiple correct answers to this question.

Difficulty:

Easy

Q 3. There is the class declaration as below:

    TDataContainerClass = Class
        private
            IndexedData: array[0..255] of Integer;
            function GetData(Index: Integer): Integer;
            procedure SetData(Index: Integer; Value: Integer);
        public
            property Data[Index: Integer]: Integer read GetData write SetData; default;
            property Tail: Integer Index 255 read GetData write SetData;
    End;

Also, integer variable val has declared.
    
Select lines of syntactically correct blocks of code, using  DataContainer: TDataContainerClass object.

Note: There can be multiple correct answers to this question.