Ah right, I was assuming a loop, which would be one instance. Hmm... I can't remember a time when I've needed to talk across component instances where using a @SessionState object didn't work. But I can see how you might want to not have the state persist between requests...
If someone doesn't come up with a better idea, you could copy the ApplicationStateWorker and create a @PerThread annotation and PerThreadWorker http://tapestry.apache.org/tapestry5/apidocs/src-html/org/apache/tapestry5/internal/transform/ApplicationStateWorker.html Josh On Wed, Nov 28, 2012 at 3:22 PM, Robert Hailey <rhai...@allogy.com> wrote: > > Unless I'm mistaken (which is possible), tapestry will create two distinct > components when building the component trees, and they will not have access > to the same variable. > > So a template like: > <html ...> > <t:widget/> > <t:widget/> > <t:widget/> > </html> > > Would yield three log messages of "rendered 1 time". > > -- > Robert Hailey > > > > On 2012/11/28 (Nov), at 5:08 PM, Josh Canfield wrote: > > > Hi Robert. > > > > Are you looking for a reason to use PreThreadValue? Or do you just want > to > > have a page/component level property that you can access for the life of > > the request? > > > > In a page or component you just declare the variable and let tapestry do > > it's magic in the background. > > > > private int widgetRenderCount = 0; > > > > void afterRender() { > > ++widgetRenderCount; > > log.debug("{} widgets have now rendered in this request!", > > count); > > } > > > > > > If you want to use it in a singleton service then you need to do the > > plumbing. > > > > Josh > > > > > > On Wed, Nov 28, 2012 at 2:32 PM, Robert Hailey <rhai...@allogy.com> > wrote: > > > >> > >> I've read the "everyone out of the pool" blog post, but have not been > able > >> to find an example of how to best use per-thread value on a page or > service > >> (seems like what's provided is an internal tapestry case). > >> > >> As a (lazy?) tapestry developer, my first thought is to try this: > >> > >> @Inject > >> private PerThreadValue<Integer> widgetRenderCount; > >> > >> Which probably isn't the expected use-case, because it doesn't work: "no > >> service implements PerThreadValue interface" (or thereabout) > >> > >> I then though I was probably looking one abstraction layer too deep (as > >> the article does talk about transparent perthread access)... so then I > >> thought of this: > >> > >> @Inject > >> @PerThread > >> private Integer widgetRenderCount; > >> > >> Which made a degree of sense because "Persist" is deprecated, but no > such > >> annotation exists. > >> > >> So then I thought I could create my own perthreadvalue-providing service > >> (to realize the first example) like this: > >> > >> public void contributeMasterObjectProvider( > >> OrderedConfiguration<ObjectProvider> configuration, > >> final PerthreadManager perthreadManager > >> ) > >> { > >> configuration.add("PerThreadValue", new ObjectProvider() { > >> public <T> T provide(Class<T> tClass, AnnotationProvider > >> annotationProvider, ObjectLocator objectLocator) { > >> return (T)perthreadManager.createValue(); > >> } > >> }); > >> } > >> > >> ... but that fails due to the "MasterObjectProvider somehow depends on > >> itself" error message and what's probably a blindingly-obvious lack of > >> knowledge on my part concerning how tapestry actually provides virtually > >> interfaced objects. > >> > >> So now I have fallen back to patterns like this, that seem to work, but > >> seem to be much clunkier than I would expect: > >> > >> @Inject > >> private PerThreadManager perThreadManager; > >> private static PerThreadValue<Integer> widgetRenderCount; > >> > >> void afterRender() { > >> if (widgetRenderCount==null) { > >> widgetRenderCount=perthreadManager.createValue(); > >> } > >> int count=widgetRenderCount.get(0); > >> count++; > >> log.debug("{} widgets have now rendered in this > request!", > >> count); > >> widgetRenderCount.set(count); > >> } > >> > >> > >> Am I missing something? If so, how is PerThreadValue intended to be > used? > >> > >> -- > >> Robert Hailey > >> > >> > >> > >
