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Autofac 2.3

De cateva zile s-a lansat o noua versiune de Autofac( v. 2.3). Am dat jos ultima versiune si am inceput sa ma joc cu acesta si iata ce am descoperit:
Ce ne ofera Autofac:
  • dependency injection;
  • inversion of control( IoC);
  • suportat de diferite platforme( ASP.NET MVC, Silverlight, etc);
Nu este atat de complex precum Windsor de la Castle Project, dar ofera functiile de baza de care am avea nevoie pentru un proiect de dimensiuni mici.
Iata cum se foloseste:
Clasa de baza prin care putem sa inregistram sau sa obtinem instance este "ContainerBuilder"
var autofac=new ContainerBuilder();
Pentru a inregistra putem folosi de metoda "Register".
autofac.Register(component=> new NumeClasa());
Pentru a obtine o componenta din container trebuie apelata metoda "Resolve":
autofac.Resolve<NumeClasa>();
In cazul in care constructorul clasei noastre are nevoie de anumiți parametrii care au fost deja înregistrați putem sa apelam metoda "Resolve" in momentul in care înregistram componenta:
autofac.Register(component=> new NumeClasa(componenta.Resolve<ClasaInregistrata>()));
Sunt cazuri cand dorim sa inregistram o componenta ca si un serviciu cu un tip diferit fata de componenta pe care vrem sa o adaugam. In acest caz metoda "As" ne vine in ajutor:
autofac.Register(component => new NumeClasa()).As<INumeClasa>();
Sunt momente cand vrem o modalitatea in care sa controlam momentul in care se face dispose pe componenta pe care am inregistrat-o. Autofac ne vine in ajutor.
autofac.Register(component => new NumeClasa()).ExternallOwned();
Dar in acest caz trebuie sa implementam interfata "IDisposable" si sa o apelam noi explicit cand este nevoie de metoda "Dispose".
In mod normal, durata de viata a unei componente este egala cu durata de viata a aplicatiei, dar putem seta ca aceasta sa existe: pe thread, pe apel HTTP sau la fiecare apel sa se creeze o noua instanta a componentei.
Pentru a avea o singura instanta in toata aplicatia trebuie sa facem in felul urmator:
autofac.Register(component => new NumeClasa()).SingleInstance();
Pentru a avea instante diferite trebuie sa apelam metoda "InstancePerLifetimeScope" in loc de "SingleInstance". Prin intermediul ei putem sa obtinem instanțe unice pe thread sau pe request.
De exemplu ca sa avem o instanta unica pe thread putem sa facem urmatorul lucru:
var container=new ContainerBuilder();
autofac.Register(component => new NumeClasa())
......
//iar in interiorul la threadul nou
using(var perThread = container.BeginLifetimeScope())
{
....
//Instanta unica pe thread.
var numeClasa = perThread.Resolve<NumeClasa>();
}
Cam complicat, nu? Puteau sa ascunda acest mecanism, iar la apelul metodei resolve sa obtinem direct o instanta unica pe thread.
Toate configuratiile se pot face si in fisierul de configurare, care sunt extrem de asemanatoare cu cele folosite de Windsor.
Concluzie: Este o solutie simpla si foarte usor de folosit, dar putem avea probleme daca dorim sa facem lucruri mai complexe, Dupa cum s-a putut observa, Autofac este destul de rudimental, nu neaparat din lipsa de functionalitati, dar are un API destul de restrans, iar unele lucruri trebuie sa le definim de fiecare data sau sa ne definim un set de extension methods.

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