On 10/03/2016 10:19, Mark Thomas wrote:
> On 10/03/2016 08:12, jimi.hulleg...@svensktnaringsliv.se wrote:


>> Then surely one can look at the other implementations, and what they did to 
>> avoid this problem. But one thing off the top of my head would be to at 
>> least avoid doing that class lookup in cases where it couldn't be a static 
>> field reference (like ${name}, since there is no dot after "name", there is 
>> no reason to check if "name" is a class reference, right?).
> It has been a while since I looked at this. I need to remind myself why
> I thought it needed to be implemented this way. I recall looking at this
> at least once before but another look wouldn't hurt.

Having reviewed this, here is some useful background.

The issue is in ScopedAttributeELResolver.

ScopedAttributeELResolver checks the page/request/session/application
context first and only if it doesn't find the attribute there does it
try loading the class.

If ScopedAttributeELResolver is asked to resolve "foo" it can't
differentiate between ${ foo } which doesn't require a class lookup and
${ foo.bar } which does require a class lookup. Therefore
ScopedAttributeELResolver will always do a class lookup if it didn't
find an a matching attribute.

These lookups pass through various standard APIs (EL and JSP specs) so
we can't simply add a flag to the method to indicate if a class lookup
is required or not.

We can't use ThreadLocals because either:
- the ThreadLocal would need to be defined in a specification class
  which isn't allowed because we can't change the public API; or
- the ThreadLocal would need to be defined in Tomcat and referenced in
  a spec class which isn't allowed because the spec JARs have to be

However, all is not lost. I think I have a solution based on ELContext
getContext()/putContext(). Keep an eye on
https://bz.apache.org/bugzilla/show_bug.cgi?id=57583 for progress reports.

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