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From Rahul Akolkar <rahul.akol...@gmail.com>
Subject Re: [JEXL] 2.0 JSR-223 initial implementation added - what next?
Date Sat, 01 Aug 2009 03:19:50 GMT
On Fri, Jul 31, 2009 at 9:42 PM, sebb<sebbaz@gmail.com> wrote:
> On 31/07/2009, Rahul Akolkar <rahul.akolkar@gmail.com> wrote:
>> On Thu, Jul 30, 2009 at 10:54 PM, sebb<sebbaz@gmail.com> wrote:
>>  > I've finished the implementation of a basic Jexl ScriptEngine for JSR-223.
>>  >
>>
>> <snip/>
>>
>>  Cool, thanks.
>>
>>  mvn package failed for me (w/ Sun 1.6), committed fix in r799750.
>
> Ah.
>
> However, I think the fix may be wrong, it should probably be a
> (String) cast instead, and should probably ignore the put if it's not
> a String.
>
<snip/>

Ah, saw the related BSF bug you logged.


>>  I'll take a look at the code itself in a few minutes.
>>
>>
>>
>>  > Several items remain to be resolved:
>>  >
>>  > The current implementation only has direct access to the ENGINE_SCOPE bindings.
>>  >
>>  > If we wish to give direct access to GLOBAL_SCOPE, how should this be managed?
>>  > Perhaps use a name prefix to indicate that the variable is intended to
>>  > be global?
>>  >
>>
>> <snap/>
>>
>>  No. The engine scope is nearest, so on read or update, check engine
>>  first and global second. No prefixes.
>>
>
> That's fine, but how does one create an entry in the global table?
> Or is that not allowed?
>
<snap/>

Thats the job of the javax.script environment. More specifically, the
ScriptEngineManager will inject the global scope bindings into the
ScriptEngine. We just have to heed those -- IOW, anything other than
put(), putAll() and remove() in the JexlContextWrapper class you have
should refer to the union of the engine and global scopes. For methods
where orders matters i.e. containsKey/Value() and get(), engine scope
beats global. Finally, IMO the clear() implementation should remain
as-is and not touch the global scope.


>>
>>  > As far as I can tell, Jexl does not have built-in output statements.
>>  > It might be useful to pre-define some variables to make this easier;
>>  > e.g. we could define OUT as System.out, which would allow the use of
>>  > OUT.println()
>>  >
>>
>> <snip/>
>>
>>  Sounds reasonable. But make the name obscure, OUT would be easily trampled IMO.
>>
>
> Yes, OUT is a bit short.
> How about System_OUT ?
> Or we could reserve a Jexl-specific prefix; this would be useful when
> using multiple languages with the same ScriptEngineManager.
>
<snip/>

Slight preference towards a JEXL-specific prefix.

-Rahul

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