Microsoft Unity IsRegister is for Debug only

This blog entry is based on this forum discussion, and of course my horrible experience with this.

So here was my code idea.

1 - Start off with an empty container.
2 - Whenever a Interface was asked to be resolved I would look on my current registered interfaces (aka using IsRegistered)
3 - If implementation was found just resolve it.
4 - If implementation was NOT found start looking on current directory for assemblies built by me (my assemblies would start with the company name)
5 - Load assembly and look for classes that implemented the interface I was looking for.
6 - If a specific name of a class was not given I would return the first class that implemented the interface asked.

Great code right? Not really, when running on a multi-threaded system I would get the follow error:

Exception:System.Exception: Collection was modified; enumeration operation may not execute.

So I started looking around and found the article mentioned above. Someone on the thread mentions that IsRegistered should only be used for Debug purpose. And it is NOT thread safe :(

Here is the code posted:

public static bool IsRegistered(this IUnityContainer container, Type typeToCheck, string nameToCheck)
        {
            Guard.ArgumentNotNull(container, "container");
            Guard.ArgumentNotNull(typeToCheck, "typeToCheck");

            var registration = from r in container.Registrations
                               where r.RegisteredType == typeToCheck && r.Name == nameToCheck
                               select r;
            return registration.FirstOrDefault() != null;
        }

The LINQ in there was my issue.

So I resorted to trying to do the register and if throw exception I catch and do my search.



try
{
    newItem = _container.Resolve(interfaceType);
}
catch (ResolutionFailedException)
{
   /// handle it here.

Have fun!