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From "Henri Biestro (JIRA)" <>
Subject [jira] [Commented] (JEXL-114) Allow scripts to create local variables // Add return keyword
Date Mon, 11 Jul 2011 21:20:00 GMT


Henri Biestro commented on JEXL-114:

Initial drop in trunk revision 1145359.

> Allow scripts to create local variables // Add return keyword
> -------------------------------------------------------------
>                 Key: JEXL-114
>                 URL:
>             Project: Commons JEXL
>          Issue Type: Improvement
>    Affects Versions: 2.0.1
>            Reporter: Henri Biestro
>            Assignee: Henri Biestro
>             Fix For: 2.0.2
> WHY:
> Not having local variables nor return in scripts is inconvenient, especially when dealing
with loops.
> This also precludes using read-only contexts easily which are really convenient when
letting end-users enter their own expressions.
> HOW:
> This could (will) be implemented by extending the parameters feature (script accept parameters
during parsing and thus arguments during evaluation) which is itself based on the notion of
'registers' - an array of objects that the interpreter allocates and uses based on script
> It only requires adding one keyword ("var" seems the obvious choice) in the .jjt.
> The "return" keyword is also an easy .jjt addition; obvious implementation is to use
an internal exception to force traversing the stack up.
> Add the "var" and "return" keyword.
> Also add methods to extract the variables (global - see JEXL-113), the parameters (used
during parsing) and the local variables (declared within) a script to help pinpoint problems
or prepare the evaluation of scripts.

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