C# Extension Method for Object

Question

Is it a good idea to use an extension method on the Object class?

I was wondering if by registering this method if you were incurring a performance penalty as it would b

Answer 1

If you truly intend to extend every object, then doing so is the right thing to do. However, if your extension really only applies to a subset of objects, it should be applied to the highest hierarchical level that is necessary, but no more.

Also, the method will only be available where your namespace is imported.

I have extended Object for a method that attempts to cast to a specified type:

public static T TryCast(this object input)
{
    bool success;
    return TryCast(input, out success);
}

I also overloaded it to take in a success bool (like TryParse does):

public static T TryCast(this object input, out bool success)
{
    success = true;
    if(input is T)
        return (T)input;
    success = false;
    return default(T);
}

I have since expanded this to also attempt to parse input (by using ToString and using a converter), but that gets more complicated.