.Net中的执行上下文和仅反射上下文是什么？

Question

I am having a hard time understanding the concepts execution context and reflection-only context in .Net. From what I understand these are two different ways to load assemblies, but I can not define them clearly.

About execution context I was able to find the documentation of the ExecutionContext class on msdn and about the reflection-only context, only how to load assemblies into it.

Can somebody provide a description of these two concepts?

Answer 1

A .NET assembly contains many things. Generally, they contain types (classes et al) and metadata (information about what those types look like, and much more).

You access metadata using reflection.

If you're only interested in the metadata, and not in actually using the types from an assembly, you can load said assembly in a reflection-only context. This enables you to load and inspect assembly metadata, but not actually instantiate types from that assembly.

A good resource about all this is CLR via C# by Jeffrey Richter . For some short info, see MSDN Blogs: Reflection Only Assembly Loading .

Also a good read is this framework documentation: Assemblies in the Common Language Runtime -> Assembly Contents :

In general, a static assembly can consist of four elements:

• The assembly manifest, which contains assembly metadata.

• Type metadata.

• Microsoft intermediate language (MSIL) code that implements the types.

• A set of resources.

And How to: Load Assemblies into the Reflection-Only Context :

The reflection-only load context allows you to examine assemblies compiled for other platforms or for other versions of the .NET Framework. Code loaded into this context can only be examined; it cannot be executed. This means that objects cannot be created, because constructors cannot be executed. Because the code cannot be executed, dependencies are not automatically loaded. If you need to examine them, you must load them yourself.

So the reflection-only context is not really a different process, or a different thread, or anything else, but just a way of loading assemblies without loading the code or dependencies therein. And the Assembly class instance representing the loaded assembly will be flagged as such using its Assembly.ReflectionOnly property .

It just loads the type metadata , so you can inspect what the types in that assembly look like.