Creating C# attribute that hooks into property's getter and setter
aop, attributes, c#
Solution
Of course, it would look similar to the following:
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
public class DataElementAttribute : Attribute
{ }
You will have to enumerate the properties with reflection to see if the property contains the attribute. (which begs the question, do you really need the attribute).
Assembly assembly = Assembly.GetExecutingAssembly();
foreach (Type type in assembly.GetTypes())
{
IList<PropertyInfo> properties = type.GetProperties();
foreach (PropertyInfo pi in properties)
{
if (type.IsDefined(typeof(DataElementAttribute), false))
{
// Perform Logic
}
}
}
However injecting Logic into the setter is a different task which would need to be done post compilation: Why is post-compilation code injection a better idea than pre-compilation code injection?
Injecting MSIL is not easy. Take a peek at this example code: http://www.codeproject.com/Articles/37549/CLR-Injection-Runtime-Method-Replacer
Problem
As a part of my API, I have an abstract BaseEntity class. I would like to provide a way to somehow hook into new properties that are introduced in the descendants of this class. What I was thinking is this: ``` public class MyEntity : BaseEntity { [DataElement] public int NewProperty { get; set; } } ``` If I could write an attribute `DataElement` that would hook in the getter and setter, then my API would be made aware of this property on access. Is this possible? UPD: I'll try to explain where this comes from. I have this BaseEntity that does not have any data by itself. Its descendants will declare what data they may hold as properties. I want to be able to iterate through all the data the object has (to store it in the database in a very specific form). One way to do it is reflection. But I thought about doing it via attributes that would register the data whenever the property is accessed.