Hi Donny, If you think a bit further, assigning the value based on the type is the only sensible way to do it. If the value was assigned based on the variable name, you would have to use that exact variable name in every component and page you want to use your SessionState-Object. That is extremely intrusive and surely not easy to maintain. And even if you were able to maintain that. What would you expect Tapestry to do in the following case? Component1 @SessionState private String eMailAddress;
Component2 @SessionState private EmailAddress emailAddress; regards nillehammer ----- original Nachricht -------- Betreff: Re: @SessionState Bug? Gesendet: Do, 06. Jan 2011 Von: Donny Nadolny<[email protected]> > Ah that's the problem then. You're expecting them to be assigned based on > the name of the variable, but @SessionState assigns them based on their > type. > > You could have in page1: > @SessionState > private String username; > > In page 2: > @SessionState > private String email; > > And they would be assigned to the same thing, because it's done based on > the > type rather than the variable name. > > I see how this would be confusing though - it does seem intuitive that they > would be assigned based on the variable name. > > On Thu, Jan 6, 2011 at 10:09 AM, Michael Gentry > <[email protected]>wrote: > > > Hi Donny, > > > > Thanks for the explanation, but the types might be a red herring. I'm > > less concerned about that than the fact that Tapestry seems to be > > assigning one of my variables to a different variable. It doesn't > > matter if the types are the same or different. I could've had: > > > > @SessionState(create=false) > > private List<String> list1; > > @SessionState(create=false) > > private List<String> list2; > > > > And I'd still expect to have two separate/distinct variables and > > lists, not two variables pointing to the same list (unless I > > specifically assigned them to the same list myself). > > > > Thanks, > > > > mrg > > > > > > On Thu, Jan 6, 2011 at 9:57 AM, Donny Nadolny <[email protected]> > > wrote: > > > Your two lists are the same - they're both of type List so they both > get > > > assigned to the same thing. See below for why. > > > > > > The solution is to make two classes, one that holds the booleans, and > one > > > that holds the strings. Technically you would only need to do that for > > one, > > > but it's probably a good idea to do it for both anyway. > > > > > > The reason why they're both considered the same: this has to do with > how > > > generics work in Java. It's called type erasure - after the class is > > > compiled, the generic type is erased, so at runtime it doesn't care > what > > the > > > type is. Generics are a compile time check. > > > > > > For example, you could do: > > > List<String> strings = new ArrayList<String>(); > > > List strings2 = strings; > > > strings2.add(new Object()); //this line is fine > > > String string = strings.get(0); //throws ClassCastException > > > > > > You might think that the strings2.add(new Object()) would have a > problem > > > because strings2 is pointing to strings which is an ArrayList<String>, > > but > > > it doesn't because at runtime it doesn't do any checks, or even know > that > > > you put <String> there (well, there's certain ways of figuring it out, > > but > > > generally just accept that it doesn't know). All it can do is give a > > warning > > > at "List strings2 = strings" because you're doing some potentially type > > > unsafe things. > > > > > > > > > On Thu, Jan 6, 2011 at 9:38 AM, Michael Gentry <[email protected] > > >wrote: > > > > > >> Hi everyone, > > >> > > >> Given the following page class: > > >> > > >> > > >> public class Bug > > >> { > > >> @Inject > > >> private Logger log; > > >> > > >> @SessionState(create=false) > > >> private List<Boolean> booleans; > > >> > > >> @SessionState(create=false) > > >> private List<String> strings; > > >> > > >> void onActivate() > > >> { > > >> log.debug("booleans = " + booleans); > > >> log.debug("strings = " + strings); > > >> > > >> if (booleans == null) > > >> booleans = new ArrayList<Boolean>(); > > >> > > >> booleans.add(Boolean.TRUE); > > >> > > >> log.debug("booleans: " + booleans); > > >> log.debug("strings: " + strings); > > >> log.debug("equal? " + booleans.equals(strings)); > > >> } > > >> } > > >> > > >> I get this output: > > >> > > >> DEBUG 2011-01-06 09:35:24,014 booleans = null > > >> DEBUG 2011-01-06 09:35:24,014 strings = null > > >> DEBUG 2011-01-06 09:35:24,014 booleans: [true] > > >> DEBUG 2011-01-06 09:35:24,014 strings: [true] > > >> DEBUG 2011-01-06 09:35:24,015 equal? true > > >> > > >> > > >> Even though I don't add anything to the strings list or even allocate > > >> the strings list, it seems to be pointing to the booleans list, which > > >> is, of course, incorrect. This seems to be happening on both 5.1 and > > >> 5.2. Am I missing something? > > >> > > >> Thanks, > > >> > > >> mrg > > >> > > >> --------------------------------------------------------------------- > > >> To unsubscribe, e-mail: [email protected] > > >> For additional commands, e-mail: [email protected] > > >> > > >> > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [email protected] > > For additional commands, e-mail: [email protected] > > > > > --- original Nachricht Ende ---- --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
