I would like to define a constrait on my custom (PostSharp) attribute. My goal is to get error or warning while compile time, if class X dont implements Y interface but it has my attribute.
So this should work:
[MyAttributeOnlyForY]
public class X : Y { ... }
but this should break the compile process:
[MyAttributeOnlyForY]
public class X { ... }
How is it possible?
The reason
This attribute works like an aspect (this is PostSharp attribute), and I want to be sure that the weaved class provides all needed information for this attribute.
I want to avoid null result on
(eventArgs.Instance as ILoggerServiceOwner)
and I think complie time checking is a good practice.
Solution
I've found a perfect start here: Validating attribute usage with P开发者_StackOverflow社区ostSharp Aspects
You could use the PostSharp method CompileTimeValidate and use reflection to check if type has a derived type. However, it may be computationally expensive do look for all types in the assembly.
I think this is not possible. A better solution might be to use the Obsolete attribute on your custom attribute constructor to warn that the target class should implement the interface Y.
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