Question

Using VB.NET on this one, in ASP.NET Web Forms.

I have a property that reads a list from a database over the entity framework, as follows:

Public ReadOnly Property MyProperty As List(Of MyType)
    Get
        Using service As New MyDatabaseService
            Return service.GetMyTypeList()
        End Using
    End Get
End Property

Because this service requires a round-trip to the database, I’d like to cache the results for future accesses during the same page lifecycle (no ViewState needed). I know this can be done as follows:

Private Property _myProperty As List(Of MyType)
Public ReadOnly Property MyProperty As List(Of MyType)
    Get
        If _myProperty Is Nothing Then
            Using service As New MyDatabaseService
                _myProperty = service.GetMyTypeList()
            End Using
        End If

        Return _myProperty
    End Get
End Property

Now for the question: is there any way to utilize caching via an attribute, to “automatically” cache the output of this property, without having to explicitly declare, test for, and set the cached object as shown?

Answer 1

The answer is sort of, but you will need to use Aspect Oriented Programming techniques in order to achieve this. Castle Windsor or PostSharp are two excellent .net frameworks that can help get you there, but this is not a light subject by any means.

Basically AOP involves wrapping up common boilerplate functionality into aspects that can be used to decorate code, leaving only the essence of what you want. This can be done dynamically at runtime as Castle does, or at compile time by IL weaving (dynamically compiling the new code into your assembly).

Each approach has its strengths and weaknesses, but I urge you to research the topic as it spans further than just caching. Many common tasks such as exception handling and logging can easily be refactored into aspects to make your code extra clean.