delphi – DWScript：传递set-of-enumerated -type将传递一个整

正如您所正确观察到的那样,这个怪癖是DWScript将静态集表示为数组.但请注意,这只是编译器前端的限制,希望有一天能够解决.见DWScript issue #10: Improve implicit casts from static arrays to sets.

以下脚本演示了编译器在set和array之间执行隐式转换的情况：

type
  TMyEnum = (meOne,meTwo);
type
  TMySet = set of TMyEnum;
type
  TMyArray = array of TMyEnum;

procedure TestSet(MySet: TMySet);
begin
  ShowMessage(integer(MySet).toString);
end;

procedure TestArray(MyArray: TMyArray);
var
  MySet: TMySet;
begin
  MySet := [];
  for var i := 0 to MyArray.Length-1 do
    Include(MySet,MyArray[i]);
  ShowMessage(integer(MySet).toString);
end;

begin
  TestSet([]);
  TestArray([]);
  TestSet([meOne]);
  TestArray([meOne]);
  TestSet([meOne,meTwo]);
  TestArray([meOne,meTwo]);

  var VarSet: TMySet = [meOne,meTwo];
  TestSet(VarSet);
  // Syntax Error: Argument 0 expects type "array of TMyEnum" instead of "TMySet"
  // TestArray(VarSet);

  var VarArray: TMyArray = [meOne,meTwo];
  TestArray(VarArray);
  // Syntax Error: Argument 0 expects type "array of TMyEnum" instead of "TMySet"
  // TestArray(VarSet);

  // Syntax Error: Incompatible types: "TMySet" and "array [0..1] of TMyEnum"  const ConstSet: TMySet = [meOne,meTwo];
  // const ConstSet: TMySet = [meOne,meTwo];
  // TestSet(ConstSet);
  // TestArray(ConstSet);

  // Syntax Error: Incompatible types: "array of TMyEnum" and "array [0..1] of TMyEnum"
  // const ConstArray: TMyArray = [meOne,meTwo];
  // TestSet(ConstArray);
  // TestArray(ConstArray);
end;

以上纯粹是脚本端实现.当您在混合中添加Delphi端实现时,它可能会出现问题.

考虑MessageDlg函数的简化实现：

Delphi边声明(通过TdwsUnit)：

type
  TMsgDlgBtn = (mbYes,mbNo,mbOK,mbCancel,etc...);
  TMsgDlgButtons = set of TMsgDlgBtn;

function MessageDlg(const Msg: string; Buttons: TMsgDlgButtons): integer;

Delphi端实现：

Info.ResultAsInteger := MessageDlg(Info.ParamAsString[0],mtInformation,TMsgDlgButtons(Word(Info.ParamAsInteger[1])),-1);

脚本用法：

begin
  // Implicit cast from array to set fails:
  // Syntax Error: There is no overloaded version of "MessageDlg" that can be called with these arguments
  // MessageDlg('Test',[mbOK]);

  var Buttons: TMsgDlgButtons = [mbOK];
  MessageDlg('Test',Buttons);
end;

现在让我们尝试使用您的解决方案,将set参数声明为数组：

Delphi边声明(通过TdwsUnit)：

type
  TMsgDlgBtn = (mbYes,etc...);
  TMsgDlgButtons = array of TMsgDlgBtn;

function MessageDlg(const Msg: string; Buttons: TMsgDlgButtons): integer;

Delphi端实现：

var
  Buttons: TMsgDlgButtons;
  i: integer;
  ButtonArray: IScriptDynArray;
begin
  ButtonArray := Info.Params[1].ScriptDynArray;
  Buttons := [];
  for i := 0 to ButtonArray.ArrayLength-1 do
    Include(Buttons,TMsgDlgBtn(ButtonArray.AsInteger[i]));
  Info.ResultAsInteger := MessageDlgEx(Info.ParamAsString[0],Buttons,-1);
end;

脚本用法：

begin
  MessageDlg('Test',[mbOK]);

  var Buttons: TMsgDlgButtons = [mbOK];
  // Note that an implicit cast from set to array is performed
  MessageDlg('Test',Buttons);
end;

在我自己的DWScript分支中,我修改了编译器以执行从枚举值数组到集合的隐式强制转换：DWScript pull request #4: Enhancement to set type.这样可以很好地工作并解决上面的所有情况,否则会失败.