Hi Ronald,
I would recommend to ways:
You should configure two GIN modules. One for authorization type A and one
for B. This will allow you to configure the dependency in different ways.
The authorization type will become a global property of your application. In
your EntryPoint, you could have something like this:
switch(authorization) {
case A:
ginjectorA.getPresenter(); // will create a presenter and its dependent
view for auth type A
case B:
ginjectorB.getPresenter(); // will create a presenter and its dependent
view for auth type B
}
You should always recognize that each 'Ginjector' is a couple of
configurations. It could look like this:
@GinModules({ModuleA.class})
public interface GinjectorA extend Ginjector {
Presenter getPresenter()
}
@GinModules({ModuleB.class})
public interface GinjectorB extend Ginjector {
Presenter getPresenter()
}
So your ModuleA's configure method can look like this:
public void configure() {
bind(Presenter.class).to(MyPresenter.class);
bind(View.class).to(ViewA.class);
}
ModuleB looks similar.
The benefit of this solution is, that you can do the same for other views
and dependencies too. You've got just one point where the global information
of the authorization type comes in.
The second way would be to create a provider that does the job. Your
presenter gets a dependency to the provider and the provider's 'get' method
does the check. A provider is similar to a factory, but it isn't one.
The idea of DI is to keep your code clean and in both cases it is done.
Regards
Jan Ehrhardt
On Mon, Jan 25, 2010 at 6:15 PM, rmuller <[email protected]> wrote:
> Hi Jan.
>
> Guess what .. I am reading "Dependency Injection" (Dhanji R. Prasanna)
> at this moment :)
> So this was one of the things why I doubt my design. But I really do
> not understand how DI (GIN) should
> be applied in my case:
> - A Presenter uses several Views. The view depends on the
> authorization (implemented as enum). Now I do something like:
>
> switch (authorization) {
> case A:
> view = new View(fieldSpecA);
> break;
> case B:
> // etc
>
> }
>
> Regards,
> Ronald
>
> On 25 jan, 17:18, Jan Ehrhardt <[email protected]> wrote:
> > The reason, why another class creats both and than puts the view into the
> > presenter is called Dependency Injection. It is a widely used pattern,
> that
> > means that you should inject dependencies into classes instead of using
> > factories or doing something like 'new DependentClass()' in the
> constructor.
> > In the best case, your presenter refers to a view interface and gets its
> > view implementation injected.
> >
> > The easiest way of doing Dependency Injection in GWT is GIN (
> http://code.google.com/p/google-gin). It allows you to configure
> > dependencies and let GIN do the creation of objects and put one into
> another
> > at runtime.
> >
> > Dependency Inection is one of the best practices in GWT (and Java too)
> > development (http://www.youtube.com/watch?v=PDuhR18-EdM)
> >
> > Regards
> > Jan Ehrhardt
> >
> >
> >
> > On Mon, Jan 25, 2010 at 2:54 PM, rmuller <[email protected]> wrote:
> > > Should not the Presenter create the view?
> > > Sometimes you need different views (based on authorization data in my
> > > case) where you can reuse the Presenter. I let the Presenter decide
> > > which view to use. I do this in the ctor.
> > > In all examples I see however, the Presenter and View are created by
> > > the parent Presenter/AppContext. Also every View has its own Presenter
> > > (1 : 1). So I wonder if my design is correct.
> >
> > > What is the general opinion about this?
> >
> > > Ronald
> >
> > > --
> > > You received this message because you are subscribed to the Google
> Groups
> > > "Google Web Toolkit" group.
> > > To post to this group, send email to
> [email protected].
> > > To unsubscribe from this group, send email to
> > > [email protected]<google-web-toolkit%[email protected]><google-web-toolkit%2Bunsubs
> [email protected]>
> > > .
> > > For more options, visit this group at
> > >http://groups.google.com/group/google-web-toolkit?hl=en.
>
> --
> You received this message because you are subscribed to the Google Groups
> "Google Web Toolkit" group.
> To post to this group, send email to [email protected].
> To unsubscribe from this group, send email to
> [email protected]<google-web-toolkit%[email protected]>
> .
> For more options, visit this group at
> http://groups.google.com/group/google-web-toolkit?hl=en.
>
>
--
You received this message because you are subscribed to the Google Groups
"Google Web Toolkit" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/google-web-toolkit?hl=en.
