When are Attribute Objects created?

Question

Since Attributes are really just Metadata attached to assemblies, does that mean that Attribute Objects are only created on request (such as when you call GetCustomAttributes)?

Answer 1

It is not quite that clean, attributes also affect code generation. Some attributes are interpreted by the compiler, [DllImport] for example. Some are discovered by the jitter, [MethodImpl] for example. This is infinitely extended to other tools and classes in the framework that were written to take advantage of attributes.

But these tools are just doing what you need to do if you want to find your own attributes, calling GetCustomAttributes() is required. That kind of code is never associated with an instance of the object, attributes apply to types.