How to identify anonymous methods in System.Reflection

Question

How can you identify anonymous methods via reflection?

Khufu

Could you say some more about what you want to accomplish? – Iveson

Answer 1

Look at the attributes of the method, and see if the method is decorated with CompilerGeneratedAttribute.

Anonymous methods (as well as other objects, such as auto-implemented properties, etc) will have this attribute added.

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For example, suppose you have a type for your class. The anonymous methods will be in:

Type myClassType = typeof(MyClass);
IEnumerable<MethodInfo> anonymousMethods = myClassType
    .GetMethods(
          BindingFlags.NonPublic
        | BindingFlags.Public 
        | BindingFlags.Instance 
        | BindingFlags.Static)
    .Where(method => 
          method.GetCustomAttributes(typeof(CompilerGeneratedAttribute)).Any());

This should return any anonymous methods defined on MyClass.

Wrongdoer

And so can any other method (or member/type). – Bobine

True - you can define this manually on any method, and fool it, but typically, this is used for anonymous methods and other compiler generated information. – Wrongdoer

For auto properties too, and on property getters and setters. – Bobine

Granted, this is not a fail-safe way to do this, as there is no such thing as "anonymous", but "anonymous" typically means a compiler-generated type. – Wrongdoer

@Leppie: I just changed the language - that help? – Wrongdoer

leppie - auto property getter/setter methods have the IsAccessor == true. – Khufu

This does not work on UWP for some reason. The attribute is not there. – Bestead

Answer 2

You cannot, because there is no such thing as an anonymous method on IL level - they're all named, and all belong to named types. And the way C# and VB compilers translate anonymous methods to named methods and types is entirely implementation-defined, and cannot be relied on (which means that, for example, it can change with any update, even in minor releases / hotfixes).

Statolatry

+1: This is, technically, the "correct" answer - but [CompilerGenerated] works fairly reliably in practice. – Wrongdoer

Answer 3

From what I can see, that Regex pattern would be:

<(\w|_)+>b_.+

Bobine