TObjectList sauber an function übergeben und wieder zurück

[Stevie]

Und deshalb mag ich interface basierte Collections so - da braucht man sich um so Zeugs gar nicht kümmern:

Delphi-Quellcode:

{$APPTYPE CONSOLE}

uses
  Spring.Collections,
  SysUtils;

type
  TTest = class
  private
    FValue: Double;
  public
    property Value: Double read FValue write FValue;
  end;

  ITestList = IList<TTest>;

function CopyTestList(const SourceList: ITestList): ITestList;
var
  i: Integer;
  lTest: TTest;
begin
  Result := TCollections.CreateObjectList<TTest>(True);

  for i := 0 to SourceList.Count - 1 do
  begin
    lTest := TTest.Create;
    lTest.Value := SourceList[i].Value;
    Result.Add(lTest);
  end;
end;

function DoAdding(const SourceList: ITestList): ITestList;
var
  i: Integer;
begin
  Result := CopyTestList(SourceList);

  for i := 0 to Result.Count - 1 do
    Result[i].Value := Result[i].Value + 5;
end;

function DoMultiplicate(const SourceList: ITestList): ITestList;
var
  i: Integer;
begin
  Result := CopyTestList(SourceList);

  for i := 0 to Result.Count - 1 do
    Result[i].Value := Result[i].Value * 5;
end;

var
  FlagAddieren: Boolean;
  FlagMultiplicate: Boolean;

function DoCalculations(const SourceList: ITestList): ITestList;
var
  temp: ITestList;
begin
  temp := SourceList;

  if FlagAddieren then
    temp := DoAdding(temp);

  if FlagMultiplicate then
    temp := DoMultiplicate(temp);

  Result := temp;
end;

procedure Start;
var
  i: Integer;
  lStartList, lResultList: ITestList;
  lTest: TTest;
begin
  lStartList := TCollections.CreateObjectList<TTest>(true);

  for i := 1 to 5 do
  begin
    lTest := TTest.Create;
    lStartList.Add(lTest);
    lTest.Value := i;
  end;

  FlagAddieren := True;
  FlagMultiplicate := True;
  lResultList := DoCalculations(lStartList);

  for lTest in lResultList do
    Writeln(lTest.Value.ToString);
end;

begin
  try
    Start;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
  Readln;
end.