Adding a Policy Injection extension to Unity - Part III
I got a request to update the policy injection extension sample from my previous post to Unity 1.1. There are not that many differences but here is the updated code:
5 namespace UnityHelpers.PolicyInjection
6 {
7 public class PolicyInjectionStrategy : BuilderStrategy
8 {
9 public override void PreBuildUp( IBuilderContext context )
10 {
11 IBuildKey buildKeyTo = context.BuildKey as IBuildKey;
12 IBuildKey buildKeyFrom = context.OriginalBuildKey as IBuildKey;
13
14 if( buildKeyFrom != null && buildKeyFrom.Type != null && buildKeyFrom.Type.IsInterface )
15 {
16 context.Existing = Wrap( context.Existing, buildKeyFrom.Type );
17 }
18
19 else if( buildKeyTo != null && buildKeyTo.Type != null && buildKeyTo.Type.IsMarshalByRef )
20 {
21 context.Existing = Wrap( context.Existing, buildKeyTo.Type );
22 }
23
24 base.PreBuildUp( context );
25 }
26
27
28 private static object Wrap( object existing, Type t )
29 {
30 if( existing != null )
31 {
32 existing = (new PolicyInjectorFactory()).Create().Wrap( existing, t );
33 }
34
35 return existing;
36 }
37 }
The ITypeBasedBuildKey is now replaced by IBuildKey in lines 11 and 12.
The code of the PolicyInjectionExtension class also changed a little bit:
4 namespace UnityHelpers.PolicyInjection
5 {
6 public class PolicyInjectionExtension : UnityContainerExtension
7 {
8 protected override void Initialize()
9 {
10 Context.Strategies.AddNew<PolicyInjectionStrategy>(UnityBuildStage.PostInitialization);
11 }
12 }
13 }
In the following thread on CodePlex a forum member states that the Builder Context is always null in the prebuild-up stage. I'm not experiencing this, but if you do his code solves your problem.
