Make both DLLs implement a common interface (ICommunicateToYourHardware) and encode the application for detecting the DLL through reflection, and not by reference.
Sample Request
The interface in this example is called IAuthenticate, but you can use any interface in it. In this case, I'm really looking for any number of IAuthenticate classes. In your case, if different DLLs are located in the same relative path, the same compilation will be loaded into different DLLs.
// We need a container for the DLL files that we find and then a container for the instances of // the plug ins created from the dlls. In this test we are only really looking for One such plug in // but I prefer to use collections for such things as it allows for a more scalable design. This technique // works for 1, 100, or more plugins and/or methods. private List<string> _DLLS; private List<iAuthenticate> _PlugIns; private int LoadPlugIns(string Path) { /// Within the designated Path (and in all subdirectories) locate all .dll files and put the path /// to these files in a collection. GetDLLS(Path); foreach (string dirName in Directory.GetDirectories(Path)) { LoadPlugIns(dirName); } // For each .dll file, inspect it (using reflection) to determine if it is of the iAuthenticate Type // if it is, create and instance of the object and store it in a collection, and assign a delegate to // invoke its Authenticate method from the host application. foreach (string DLL in _DLLS) { Assembly myAssembly = Assembly.LoadFrom(DLL); Type[] Types = myAssembly.GetTypes(); foreach (Type myType in Types) { Type T = myType.GetInterface("iAuthenticate"); if (T != null) { if (_PlugIns == null) { _PlugIns = new List<iAuthenticate>(); } _PlugIns.Add((iAuthenticate)myAssembly.CreateInstance(myType.FullName)); } } foreach (iAuthenticate iAuth in _PlugIns) { this.Authorize += iAuth.Authenticate; } } return _PlugIns.Count; } private void GetDLLS(string Path) { if (_DLLS == null){_DLLS = new List<string>();} foreach (string filename in Directory.GetFiles(Path, "*.dll")) { _DLLS.Add(filename); } }
once we have a set of links through reflection, we can call its methods as follows:
private void btnLogon_Click(object sender, EventArgs e) { try { if (Authorize.Invoke(txtUsername.Text, txtPassword.Text, txtPath.Text)) { this.BackgroundImage = TelefloraDemo.Properties.Resources._189469; this.pnlLogon.Visible = false; MessageBox.Show("You have Logged On!"); } } catch (AuthenticationException aex) { DemoCode.LogException(aex); MessageBox.Show(aex.ToString()); } catch (Exception ex) { DemoCode.LogException(ex); MessageBox.Show("No Authenticator"); } } public delegate bool Authenticate(string Username,string Password,string Path); public event Authenticate Authorize;
Now, obviously, your mileage may vary, but this should make you successful. (Yes, there are other ways, I like this one ..)