Yes, I think 90% of the time something like this is what you'd want.
The place I can see the manager being useful is more to help
create/associate model objects with widgets, which would only be something
you'd need for reasonably complex applications.
interface QuestionAnswerPair {
Question getQuestion();
Answer getAnswer();
}
class QuestionAnswerManager implements DataManager<QuestionAnswerPair,
HasText & HasId> {
}
public abstract class MyTextQuestion extends Composite{
QuestionAnswerPair model = getQuestionPairManager().getData(this);
...
}
On Fri, Oct 3, 2008 at 12:02 PM, Isaac Truett <[EMAIL PROTECTED]> wrote:
>
> Let me offer a use case and see if that helps. If I'm just off base
> here, do please let me know.
>
> First, some definitions (please excuse the crudity of these models. I
> didn't have time to build them to scale):
>
> public interface HasData<T> {
> public T getData();
> public void setData(T data);
> }
>
> public abstract class Form<T> extends Composite implements HasData<T> {
> // Some reusable form-y stuff here.
> }
>
> public abstract class ContrivedReadOnlyWidget<T> extends Composite
> implements HasData<T> {
> // A contrived example of something else that HasData.
> }
>
> public class Foo {
> // My data
> }
>
> public class LoadFooCommand implements Command {
> private String fooId;
> private HasData<T> dataWidget;
>
> public LoadFooCommand(String fooId, HasData<Foo> dataWidget) {
> this.fooId = fooId;
> this.dataWidget = dataWidget;
> }
>
> // Load the Foo with the specified into the dataWidget.
> public void execute() {
> Foo myFoo = getFoo(fooId);
> dataWidget.setData(myFoo);
> }
> }
>
> I have a pattern very close to this in my current project. Basically,
> I can reuse simple Commands to do things like populate forms or
> display pages with existing database records.
>
> What would you do with the DataManager interface in this example? Or
> if it doesn't apply in this example, what would be an example of how
> it would be used?
>
>
>
>
>
> On Fri, Oct 3, 2008 at 11:25 AM, Emily Crutcher <[EMAIL PROTECTED]> wrote:
> > Having worked on similar projects, I am very enthusiastic about the idea
> of
> > creating a full gwt forms module, as apart from it being a true pain in
> the
> > neck to create them by hand, improving the overall quality of such forms
> > will, in the long term, save lives, so I'm looking forward to this work.
> >
> > -------------------
> >
> > The same widgets might be used to get/set different data types and it
> > separates the presentation logic from the data model, so separating the
> two
> > seems to make some sense. On the other hand, it means that there is no
> > simple interface that can be used when you actually do have data model
> > objects:
> >
> > So what if we combined the two:
> >
> > public interface HasData<T> {
> > public T getData();
> > public void setData(T data);
> > }
> >
> > then:
> >
> > public interface DataManager<T, S extends HasData> {
> > public HasData getData(T widget);
> > public void setData(T widget, S data);
> > }
> >
> >
> >
> > On Fri, Oct 3, 2008 at 11:06 AM, Isaac Truett <[EMAIL PROTECTED]> wrote:
> >>
> >> Why wrappers? Why not have the widgets simply implement a HasData
> >> interface?
> >>
> >> public interface HasData<T> {
> >> public T getData();
> >> public void setData(T data);
> >> }
> >>
> >> Maybe I'm just not seeing your use case.
> >>
> >>
> >>
> >> On Fri, Oct 3, 2008 at 10:55 AM, Arthur Kalmenson <
> [EMAIL PROTECTED]>
> >> wrote:
> >> >
> >> > Hello every,
> >> >
> >> > Just a little backgrounder for this RR. For some time now, a coworker
> >> > and I have been working on and off on a library/framework to simplify
> >> > creation of GWT applications, specifically those that cover most of
> >> > our use cases. For the most part, the applications we build involve
> >> > filling out rather large forms, retrieving data, generating reports,
> >> > etc. Building these large forms by hand is very tedious, so we created
> >> > an open source project called Mount Sinai Hospital Application Builder
> >> > (mshab) which you can find here: http://code.google.com/p/mshab/.
> >> >
> >> > I started to overhaul the project to make it easier to use and easier
> >> > to extend. As I started the overhaul, I noticed that the incubator
> >> > started to get populated with a lot of similar widgets and libraries
> >> > that I was redeveloping. I contacted Emily Crutcher about the
> >> > Validation aspect and we ended up talking a bit about the incubator. I
> >> > decided that it'll be best to try to commit back to the incubator so
> >> > we could avoid having to throw away our code after the incubator
> >> > implemented the same ideas. I'll start making RRs about the various
> >> > parts that we were working on to get feedback and hopefully
> >> > incorporate it into the incubator.
> >> >
> >> > Now, to the meat of the post. Right now, extracting data from widgets
> >> > is very different depending on the widget. From a TextBox, you call
> >> > textBox.getText(). For a ListBox you call
> >> > listBox.getValue(listBox.getSelectedItem()). Setting the data is
> >> > different too, and sometimes pretty "complex" (ListBox involves a
> >> > loop, etc). Therefore, I'm proposing a common interface that wraps
> >> > around core GWT widgets and provides one way to extract and set data
> >> > to widgets. There are a number of use cases where this can be applied.
> >> > Some good examples are validation and simple data binding.
> >> >
> >> > The interface is a straight forward generic interface that works with
> >> > a generic widget and a generic data type (comments removed):
> >> >
> >> > public interface DataManager<T, S> {
> >> >
> >> > public S getData(T widget);
> >> >
> >> > public void setData(T widget, S data);
> >> > }
> >> >
> >> > Here's an example of how it would be used to manage TextBoxBase
> >> > widgets.
> >> >
> >> > public class TextBoxBaseDataManager implements
> >> > DataManager<TextBoxBase, String> {
> >> >
> >> > public String getData(TextBoxBase widget) {
> >> > return widget.getText();
> >> > }
> >> >
> >> > public void setData(TextBoxBase widget, String data) {
> >> > widget.setText(data);
> >> > }
> >> > }
> >> >
> >> > To help developers easily get the appropriate DataManager for a
> >> > specific widget, I created a DataManagerCollection interface where you
> >> > can get the specific DataManager for a given widget and then start
> >> > working with it. The developer can either use existing
> >> > DataManagerCollection implementations or wire their own.
> >> >
> >> > public interface DataManagerCollection {
> >> >
> >> > public boolean hasDataManager(Widget widget);
> >> >
> >> > public DataManager<?, ?> getDataManager(Widget widget);
> >> >
> >> > public void setDataManager(Widget widget, DataManager<?, ?>
> >> > dataManager);
> >> > }
> >> >
> >> > We're currently working on creating wrappers for all the core GWT
> >> > widgets and the incubator ones. Feedback would be much appreciated.
> >> > Thank you for your time.
> >> >
> >> > Best regards,
> >> > Arthur Kalmenson
> >> > >
> >> >
> >>
> >>
> >
> >
> >
> > --
> > "There are only 10 types of people in the world: Those who understand
> > binary, and those who don't"
> >
> > >
> >
>
> >
>
--
"There are only 10 types of people in the world: Those who understand
binary, and those who don't"
--~--~---------~--~----~------------~-------~--~----~
http://groups.google.com/group/Google-Web-Toolkit-Contributors
-~----------~----~----~----~------~----~------~--~---
