Passing a method-containing record between host application and DLL

Question

Is it possible (without the use of Runtime Packages or the Shared Memory DLL) to pass a Record type between the host application and a DLL module where the Record type contains Functions/Procedures (Delphi 2006 and above)?

Let's presume for the sake of simplicty that our Record type doesn't contain any String fields (as this of course requires the Sharemem DLL), and here's an example:

TMyRecord = record
  Field1: Integer;
  Field2: Double;
  function DoSomething(AValue1: Integer; AValue2: Double): Boolean;
end;

So, to state this simply: can I pass an "instance" of TMyRecord between the host application and a DLL (in either direction), without the use of Runtime Packages or Shared Memory DLL, and execute the DoSomething function from both the Host EXE and the DLL?

Answer 1

I would not suggest that, whether it works or not. If you need the DLL to operate on TMyRecord instances, the safest option is to have the DLL export plain functions instead, eg:

DLL:

type
  TMyRecord = record 
    Field1: Integer; 
    Field2: Double; 
  end; 

function DoSomething(var ARec: TMyRecord; AValue1: Integer; AValue2: Double): Boolean; stdcall;
begin
  ...
end;

exports
  DoSomething;

end.

App:

type 
  TMyRecord = record  
    Field1: Integer;  
    Field2: Double;  
  end;  

function DoSomething(var ARec: TMyRecord; AValue1: Integer; AValue2: Double): Boolean; stdcall; external 'My.dll';

procedure DoSomethingInDll;
var
  Rec: TMyRecord;
  //...
begin 
  //...
  if DoSomething(Rec, 123, 123.45) then
  begin
    //...
  end else
  begin
    //...
  end;
  //...
end;