What does WBP stand for?
On Wed, Jun 23, 2010 at 6:40 AM, Konstantin.Scheglov <
konstantin.scheg...@gmail.com> wrote:
>
> To support UiBinder in GWT Designer we need to have several changes
> in UiBinder generators, writer and parsers.
> I will describe below these changes as they are done now.
> In real patch I will group as much implementation details as
> possible into single class like DesignTimeUtils or GWTDesignerSupport.
> It will check for GWT Designer presence and do something only in this
> case.
>
> So, main question is following. Will GWT team accept patch with such
> changes?
> This would allow us avoid creating internal patches for 2.0 and each
> future version of GWT.
>
>
> 1. Declare in binder implementation interface and field with it.
> Something like this:
> public static interface WBPObjectHandler {void handle(String
> path, Object object);}
> public WBPObjectHandler wbpObjectHandler;
> In method createAndBindUi() directly after creating each Widget
> instance (but before applying setX() methods) "wbpObjectHandler" is
> used to notify GWT Designer about new widget and its path in XML. GWT
> Designer bind Widget instance to model (using path) and also asks
> default values for all properties using getX() methods.
>
> Path in XML is "/" separated string of indexes.
> For example in
> <ui:UiBinder>
> <ui:style/>
> <g:FlowPanel styleName="{style.panel}">
> <g:Button text="New Button"/>
> </g:FlowPanel>
> </ui:UiBinder>
>
> "0/1" is FlowPanel
> "0/1/0" is Button
>
This doesn't sound like a tooling hook, it sounds like a data binding
framework, and a very run time one — not really how we like to do things,
and not how we're gearing up to write our own data binding support this
month.
What is the model object we're talking about? Does GWT designer impose a
particular architecture on its users, or is it an implementation detail of
designer itself?
I'd be a lot more comfortable with hooks that happen at code generation
time, e.g. to allow you to navigate the model binder builds before things
get written to disk.
> 2. Declare in binder implementation Map with values of attributes.
> public final java.util.Map wbpAttributes = new
> java.util.HashMap();
> and fill it, here is example if code generated for ui.xml above
>
> if (wbpObjectHandler != null) wbpObjectHandler.handle("0/1/0",
> f_Button2);
> f_Button2.setText("New Button");
> wbpAttributes.put("0/1/0 text", "New Button");
> f_FlowPanel1.add(f_Button2);
> if (wbpObjectHandler != null) wbpObjectHandler.handle("0/1",
> f_FlowPanel1);
> f_FlowPanel1.setStyleName("" + style.panel() + "");
>
> GWT Designer needs to know attribute values to show them to user in
> properties table. Not all properties have getter, so we can not get
> these values for existing Widget object.
>
Again, this smells of reflection and runtime data binding. I need more
context.
>
>
> 3. In special parsers for panels, remember also values of attributes
> for artificial elements. For example "Cell" in CellPanelParser (and
> "Dock" in DockPanel).
>
> // Parse horizontal and vertical alignment attributes.
> if (cellElem.hasAttribute(HALIGN_ATTR)) {
> String value = cellElem.consumeAttribute(HALIGN_ATTR,
> hAlignConstantType);
> writer.addStatement("%1$s.setCellHorizontalAlignment(%2$s,
> %3$s);",
> fieldName, childFieldName, value);
> //XXX <Instantiations
> writer.addStatement("wbpAttributes.put(\"%s\", %s);",
> widgetElem.getPath() + " Cell." + HALIGN_ATTR, value);
> //XXX >Instantiations
> }
>
>
>
> 4. To allow quick updates of design canvas as user changes properties,
> without reloading GWT context each time, we should:
> 4.1. Generate Binder implementation class with new name each time, so
> be able to define each time new class in same ClassLoader. Right now
> we just add current time to the name of class.
> //XXX <Instantiations
> // generate class with new name each time, to allow refresh in
> same ClassLoader
> implName += "_wbp" + System.currentTimeMillis();
> //XXX >Instantiations
>
We could not do this with a timestamp, as it's important that the same code
always produce the same binary. Would appending an md5 sum to the class name
do the trick?
> 4.2. To parse/render UI.XML file content without saving, i.e. from
> memory/editor, generate should try to read document from memory.
> Something like this:
> private Document getW3cDoc(MortalLogger logger, String templatePath)
> throws UnableToCompleteException {
> //XXX <Instantiations
> {
> String content = System.getProperty("wbp.gwt.UiBinder " +
> templatePath);
> if (content != null) {
> Document doc = null;
> try {
> doc = new
> W3cDomHelper(logger.getTreeLogger()).documentFor(content);
> } catch (SAXParseException e) {
> logger.die("Error parsing XML (line " + e.getLineNumber() +
> "): "
> + e.getMessage() + " " + content, e);
> } catch (Throwable e) {
> logger.die("Error parsing XML " + content, e);
> }
> return doc;
> }
> }
> //XXX >Instantiations
>
> URL url =
> UiBinderGenerator.class.getClassLoader().getResource(templatePath); //
> this is default implementation
>
Something like this seems reasonable. @scott, since we're talking about a
development tool hook here, would there be any need to go through the
resource oracle?
>
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>
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