GWT and MVP; Rendering logic

Question

i apologise if this is a silly question however i recently have the following use case.

I have a component which I want to reuse, in one instance i want to be able to edit the data and in another instance i only want it to be viewable.

so this means in one use case i want to render say labels 1, 2 and 3 along with an edit button and in the second use case i do not want to render the edit button.

Now I am using the mvp pattern and I am currently of the understanding that logic should not appear in the presenter.

My question is: if i want to render a component based on logic from the presenter how do i do this without introducing logic in the view.

short examples are very welcome :)

Answer 1

Back-end > sends > the model > to > the presenter > which calls display method on > the view

Your model would be a POJO (typically a shared object retrieved from the back-end). The presenter would make and RPC call to retrieve it. Based on the model configuration the presenter will or will not call some "setAsEditable(Boolen editable)" method available on the view when receiving the model.

The view > sends events to > the presenter > which updates > the model > and sends it to > the back-end

When the user make some action on the view the presenter will receive a notice of it (through events or based on an interface) and update the model. Note the model update logic (like the display logic) is also meant to be in the presenter. The model would then be pushed back to the back-end by the presenter (via RPC). Business logic stays in the back-end.

Personal note:

Hardcore MVPers would enforce strict loose coupling between components, but it often involves writing lots of event classes and/or interfaces (some call it boilerplate). Be pragmatic. I sometimes avoid using this architecture when I know my components won't be reused, and wait until the need for reuse comes to me.

But if you can manage to stay pure, you're good !