This is a working solution for your problem:
Add the 2 DLL's (x86 and x64) to your solution in a subfolder. Make them "Copy if newer"
Reference the correct DLL you use for development for debugging from the 2 DLL's you added. Make it Copy Local=false.
What this does is that when you app starts the DLL is not autoloaded. It will not be loaded until you use a Type from that assembly. Once that happens an event will be triggered in .Net that asks where it can find your assembly.
So sometime before the first use of that assembly make sure you attach yourself to that event.
AppDomain.CurrentDomain.AssemblyResolve += CurrentDomain_AssemblyResolve;
In the content of the handler make sure you load the DLL (x86 or x64) when it asks for it.
static System.Reflection.Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args) {
if (args.Name.Equals("MyFullAssemblyName")) {
var path = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
if (IntPtr.Size > 4) {
var dll = System.IO.Path.Combine(path, @"MySubDir\MyDLL_x64.dll");
return System.Reflection.Assembly.LoadFile(dll);
}
else {
var dll = System.IO.Path.Combine(path, @"MySubDir\MyDLL.dll");
return System.Reflection.Assembly.LoadFile(dll);
}
}
return null;
}
Voila. You can now run your app as both 32 bit and 64 bit.
Alternatively to adding the DLLs in a subfolder, you can make them as Embedded Resources, and then load them like this:
static System.Reflection.Assembly CurrentDomain_AssemblyResolve(object sender, ResolveEventArgs args) {
if (args.Name.Equals("MyFullAssemblyName")) {
var ass = Assembly.GetExecutingAssembly();
if (IntPtr.Size > 4) {
var strm = ass.GetManifestResourceStream("the.resource.name.for.MyDLL_x64.dll");
var data = new byte[strm.Length];
strm.Read(data, 0, data.Length);
return Assembly.Load(data);
}
else {
var strm = ass.GetManifestResourceStream("the.resource.name.for.MyDLL.dll");
var data = new byte[strm.Length];
strm.Read(data, 0, data.Length);
return Assembly.Load(data);
}
}
return null;
}
This does not work for all assemblies. Some "hybrid" assemblies tends to fail unless they are loaded from disk (can be solved by writing them to disk just before loading).
