I am trying to use Interception Call Handler and Handler Attributes on my interfaces (or implementation). Lets say my Interface has two methods DoSomething() and DoSomethingElse(), and I only have the interceptor for DoSomethingElse(); when I resolve my main interface the constructor for the Call Handler get called even if I never invoke DoSomethingElse().
I tried this by resolving to Lazy(of IMainInterface) but the moment I call the function DoSomething() the Call Handler is still created unnecessarily. Is there a way to prevent this from happening either by code or configuration. Here is my sample implementation
Handler Attribute and Call Handler
<AttributeUsage(AttributeTargets.Method)>
Public Class NormalSampleAttribute
Inherits HandlerAttribute
Public Sub New()
Console.WriteLine("Constructor of Normal Sample Attribute")
End Sub
Public Overrides Function CreateHandler(container As Microsoft.Practices.Unity.IUnityContainer) As Microsoft.Practices.Unity.InterceptionExtension.ICallHandler
Console.WriteLine("Create Handler")
Return New SampleCallHandler
End Function
End Class
Public Class SampleCallHandler
Implements ICallHandler
Public Sub New()
Console.WriteLine("Constructor of Sample Call handler")
End Sub
Public Function Invoke(input As IMethodInvocation, getNext As GetNextHandlerDelegate) As IMethodReturn Implements ICallHandler.Invoke
Console.WriteLine("Invoke of Sample Call handler - " & input.MethodBase.Name)
Return getNext.Invoke(input, getNext)
End Function
Public Property Order As Integer Implements ICallHandler.Order
End Class
Interface and implementation
Public Interface IMainInterface
Sub DoSomething()
<NormalSample()>
Sub DoSomethingElse()
End Interface
Public Class MainClass
Implements IMainInterface
Public Sub New()
Console.WriteLine("main class - Constructor")
End Sub
Public Sub DoSomething() Implements IMainInterface.DoSomething
Console.WriteLine("main class do something...")
End Sub
Public Sub DoSomethingElse() Implements IMainInterface.DoSomethingElse
Console.WriteLine("main class do something else...")
End Sub
End Class
Main module to register and execute the method
Module Module1
Public container As IUnityContainer
Sub Main()
container = New UnityContainer
DoRegistrations()
Console.WriteLine("Before lazy Resolve")
Dim lmc As Lazy(Of IMainInterface) = container.Resolve(Of Lazy(Of IMainInterface))()
Console.WriteLine("Before making lazy function call")
lmc.Value.DoSomething()
Console.ReadLine()
End Sub
Sub DoRegistrations()
container.AddNewExtension(Of InterceptionExtension.Interception)()
container.RegisterType(Of IMainInterface, MainClass)()
container.Configure(Of Interception).SetDefaultInterceptorFor(Of IMainInterface)(New InterfaceInterceptor)
End Sub
End Module
It produces the following output:
Before lazy Resolve
Before making lazy function call
main class - Constructor
Constructor of Normal Sample Attribute
Create Handler
Constructor of Sample Call handler
main class do something...
Even though DoSomethingElse() is never called the cost of the handler creation is being added on all flows. Is there any way to avoid this? Any help is appreciated.
Thanks in advance! SV