Catch (Exception e): Right or wrong?

I've long heard that you shouldn't throw a type Exception in C#. I try to always throw a type derived from Exception.

In addition, I've also read many brief snippets over the years that says you shouldn't write C# code like:

catch(Exception e)
{
...
}

I recently read the best explanation of this in Microsoft's MSDN Magazine (Feb. 2009). The article is entitled Handling Corrupted State Exceptions and would highly recommend those programming in C# to read the full article. It also provides details about how exception handling will change a bit in .NET 4.0.

A read well worth it!

http://msdn.microsoft.com/en-us/magazine/dd419661.aspx

Plug-in architecture (dynamically loading DLLs) using LINQ

For implementing a plug-in architecture using the strategy pattern, this is my preferred way of loading some interfaces (DLLs) at runtime. Make sure you look at the second code example showing how to do the same thing in LINQ.

public List<T> LoadDLL<T>(string path, string pattern)
{
    List<T> plugins = new List<T>();
    foreach (string s in Directory.GetFiles(Path.GetFullPath(path), pattern))
    {
        foreach (Type t in Assembly.LoadFile(s).GetTypes())
        {
            if (!t.IsAbstract && typeof(T).IsAssignableFrom(t))
            {
                plugins.Add((T)Activator.CreateInstance(t));
            }
        }
    }

    return plugins;
}

Now using LINQ...

public List<T> LoadDLL<T>(string path, string pattern)
{
    return Directory.GetFiles(Path.GetFullPath(path), pattern)
        .SelectMany(f => Assembly.LoadFile(f).GetTypes()
            .Where(t => !t.IsAbstract && typeof(T).IsAssignableFrom(t))
            .Select(t => (T)Activator.CreateInstance(t)))
        .ToList();
}

If you want to load an assembly and all the dependent DLLs, you can use the same LINQ query, but use LoadFrom rather than LoadFile.

public List<T> LoadDLL<T>(string path, string pattern)
{
    return Directory.GetFiles(Path.GetFullPath(path), pattern)
        .SelectMany(f => Assembly.LoadFrom(f).GetTypes()
            .Where(t => !t.IsAbstract && typeof(T).IsAssignableFrom(t))
            .Select(t => (T)Activator.CreateInstance(t)))
        .ToList();
}

This can then be called using:

List<Foo> foos = LoadDLL<Foo>(@".\", "*.dll");