Sharing an ADO Connection across a DLL boundary - delphi

Question

We would like to share an ADOConnection across a DLL boundary (Delphi to Delphi at the moment, though could also be C# to Delphi in the near future).
As we would like the flexibility to call the DLL from c# in future, we were hoping to be able to define the DLL call using _Connection as a parameter. Something like:
procedure DoStuff (ADOConnection: _Connection)
var
InnerConnection: TADOConnection;
begin
InnerConnection := TADOConnection.create(nil);
try
InnerConnection.ConnectionObject := ADOConnection;
DoMoreStuff(InnerConnection);
finally
InnerConnection.free;
end;
end;
Unfortunately, the TADOConnection destructor code closes the connection passed into it, which is an unwanted side-effect. Adding
InnerConnection.ConnectionObject := nil
prior to the free doesn't do anything, as it's caught by
if Assigned(Value) = nil
in TADOConnection.SetConnectionObject, which results in the call not doing anything.
Is there a better way of achieving this? Passing the connection string is an alternative, but would mean that we would have to deal with username/password issues and encryption across the boundary. Passing the TADOConnection is another option, but that prevents calling from other languages.
Edit: For clarity, the Username/Password of the original TADOConnection object is set using the .Open routine, so these details aren't in the connection string (in fact, the wrong username is usually stored, as it's the name used to 'test connection' in the MS UDL editor)

Answer 1

You can try this way:
type TInit_StFattDLL = procedure( var DataBase:TAdoConnection);
var Init_StFattDLL:TInit_StFattDll;
The caller is:
Function ConnectDll():Boolean;
var
handleDll:THandle;
begin
handleDll := LoadLibrary('mydll.DLL');
#Init_StFattDLL := GetProcAddress(handleDll , 'myConnectFunction');
if #Init_StFattDLL <> nil then
begin
Init_StFattDLL(ADOConnection1);
result:=true;
end
else
result:=false;
end;
into the the dll put the following:
in the project file put the exports:
Exports myConnectFunction;
global section:
var Database:TAdoConnection;
the exported procedure is the following:
procedure myConnectFunction( var MyDataBase:TAdoConnection);export;
begin
Database:=MyDataBase;
end