inversion of control - How to force a registered "ambient" object to be resolved? -

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by "ambient object," mean 1 present doing in background, nobody else knows about. example, object hooks events on variety of other objects , logs messages when fire.

the problem is: since nobody except unity builder knows object exists, nobody resolves it, , never gets created. there elegant solution problem?

i create dummy class so:

public class ambientobject {    public object theobject { get; set; } }

create factory methods return ambients inside ambientobject wrappers each case, register them unity, , have composition root container.resolveall<ambientobject>() (and ignore return value) ensure they're created, that's not elegant.

it sounds want unity automatically resolve instance in background.

there's lot of ways of doing it, can think of two:

1. when creating container lazy.

public static class ioccontainer {      private imyambient _ambient;     private static readonly lazy<iunitycontainer> container = new lazy<iunitycontainer>(() =>     {         var container = new unitycontainer();          // registration.         container.registertype<imyambient, ambient>();         _ambient = container.resolve<imyambient>();         _ambient.dostuff();         return container;     });      public static iunitycontainer instance     {         { return container.value; }     } }

2. register unitycontainerextension.

public static class ioccontainer {     private static readonly lazy<iunitycontainer> container = new lazy<iunitycontainer>(() =>     {         var container = new unitycontainer()             .addnewextension<ambientcreation>();         container.registertype<imyambient, ambient>();         return container;     });      public static iunitycontainer instance     {         { return container.value; }     } }  public class ambientcreation: unitycontainerextension {      protected override void initialize()     {         // using precreation, may want one?         context.strategies.addnew<ambientcreationstrategy>(unitybuildstage.precreation);      } }  public class ambientcreationstrategy: builderstrategy {      private iunitycontainer getunityfrombuildcontext(ibuildercontext context)     {         var lifetime = context.policies.get<ilifetimepolicy>(namedtypebuildkey.make<iunitycontainer>());         return lifetime.getvalue() iunitycontainer;     }      public override void prebuildup(ibuildercontext context)     {         // runs @ every resolve. can decide when create ambient object.     } }

i'm using later create log-objects based on stack. maybe can in right direction? downside both options there's no magic going on @ all. moves logic part of application. , 1 may argue buildstrategies aren't supposed used this.

more info: http://weblogs.asp.net/ricardoperes/unity-part-10-custom-build-strategies


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