> The reason why they're both considered the same: this has to do with how
> generics work in Java.
I'm building in better generics support for 5.3, this seems like something I
can make work. All of the generic information is available for fields,
methods, and method parameters via reflection. Luckily most everything
Tapestry needs to do is acting on things that are compiled in to the class!
Currently the current 5.3 codebase has support for generic components, and
the Loop has been updated to pull the type information for the value from
the bound source parameter. If you have a List<Person> then you can access
the properties of Person;
@Property
private List<Person> personSource;
<t:loop t:id="personLoop" source="personSource">
<div id="person_${personLoop.index}">${personLoop.value.name}</div>
</t:loop>
Next on my list is generic services (@Inject GenericDAO<Person> personDao;)
it's implemented but working through tests/use cases. I'll add @Persist.
Josh
On Jan 6, 2011 6:57 AM, "Donny Nadolny" <donny.nado...@gmail.com> 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 <mgen...@masslight.net
>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: users-unsubscr...@tapestry.apache.org
>> For additional commands, e-mail: users-h...@tapestry.apache.org
>>
>>
