CODEWITHSUNDEEP
delphicastingrttidelphi-10.1-berlin
John
John

Reputation: 281

Rtti invoke a class method says invalid type cast

I have made a unit that's very generic and settings objects in this are all TObjects i don't want to make uses of any units that's why i'm doing this. So my approach is to use RTTI to call everything. But now i face a problem where i can call all the functions and give arguments and everything but when the method is a class procedure/function i can't call it and it says invalid type cast.

I checked on embarcadero's website it says that when we call rtti.invoke on a classmethod we have to set the first argument in Args as a class reference. I tried that but it doesn't work. Take a look at my code:

function TSomething.ExecMethodAndRet(MethodName: string;
  Args: array of TValue): TObjectList<TObject>;
var
 R : TRttiContext;
 T : TRttiType;
 M : TRttiMethod;
 lArgs : array of TValue;
 i : integer;
begin
  T := R.GetType(MainObj.ClassInfo);
  for M in t.GetMethods do
    if (m.Parent = t) and (UpperCase(m.Name) = UpperCase(MethodName))then
    begin
      if (m.IsClassMethod) then
      begin
        for I := 0 to Length(Args) do
          lArgs := [args[i]];
        lArgs := [MainObj] + lArgs;
        result := M.Invoke(MainObj, Args).AsType<TObjectList<TObject>>; <- this will say invalid type cast
      end
      else
        result := M.Invoke(MainObj, Args).AsType<TObjectList<TObject>>; <- this one works when it's not a classMethod that's why i made a condition
    end;
end;

I don't know what i'm doing wrong. Maybe it's not possible to do it without knowing the type of the object. My Main Obj is a TObject that is of the required type and i can call the methods of it. But That class procedure is really giving me a hard time.

Someone knows how i could achieve this?

Upvotes: 2

Views: 1617

Answers (1)

Jan Lauridsen
Jan Lauridsen

Reputation: 586

Instead of the instance use

M.Invoke(MainObj.ClassType,

Upvotes: 5

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