When you ask for an A, Guice will create a B on demand to fill your A's b
field; to do that, it will create a C to fill B's c field.
If you do this:
A a = Guice.createInjector().getInstance(A.class);
a.b.useC();
doSomething() will in fact be called.
On Thu, Sep 11, 2008 at 3:19 PM, Pyrolistical <[EMAIL PROTECTED]> wrote:
>
> Here's an example of why I don't "get" Guice.
>
> class A {
> @Inject B b;
> }
>
> class B {
> @Inject C c;
>
> publc void useC() {
> c.doSomething();
> }
> }
>
> If you use an injector to get an instance of A, it doesn't Inject the
> member c in class B. This is my main problem with Guice.
>
> I know the pattern is to do this:
> class B {
> C c;
>
> @Inject
> public B(C c) {
> this.c = c;
> }
>
> publc void useC() {
> c.doSomething();
> }
> }
>
> But that is unacceptable. I don't want Guice to handle the creation
> of B, I just want it to provide C to B without using the constructor.
> So the other solution is to use a static field.
>
> class B {
> @Inject static C c;
>
> publc void useC() {
> c.doSomething();
> }
> }
>
> But now you have to add binder.requestStaticInjection(B.class) to your
> module. If I use C in a lot of classes, I don't want to manually add
> each requestStaticInjection to the module!
>
>
> I don't understand why Guice cannot inject C in my original example,
> or if its possible to use Guice to make it work without having to
> modify the constructor or dozens of lines of requestStaticInjection.
>
> In my head, this is how I think Guice should work. Guice uses a
> custom classloader such that when it sees @Inject, it checks the
> module for the right class. You can still run through the classpath
> to check that you have something bound to all members that use @Inject
> and this can be cached to file too!
>
> Then this way you don't ever need to use
> injector.getInstance(RootClass.class), you just new a RootClass, or
> any class for that matter.
>
> If Guice wants us to add members to the constructor for them to be
> inject, then I feel there's not point in using Guice. It is not more
> difficult for me to keep a reference to C and pass it to B's
> constructor myself.
>
> Am I missing something to "get" Guice?
> >
>
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