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From "Henri Biestro (Jira)" <j...@apache.org>
Subject [jira] [Commented] (JEXL-307) Variable redeclaration option
Date Wed, 02 Oct 2019 10:04:00 GMT

    [ https://issues.apache.org/jira/browse/JEXL-307?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16942675#comment-16942675
] 

Henri Biestro commented on JEXL-307:
------------------------------------

1 - Not sure I fully grasped your view on globals. Your example about variable loop visibility
does have an effect; the 'i' variable outside the loop _could_ be considered as a global.
The current stance - shared with consultants dealing with huge scripts - is that a variable
symbol should be either local or global but should *not* be allowed to be both. In essence,
if a symbol is used as a parameter or local variable in a script, it can no longer be considered
a global. 
2 - Hoisted variables handling as you describe seems sound.
3 - Pragmas are out-of-flow and should be considered as script meta-data. Some users prefer
having them declared at end of script, some at start, some at point of impact... Better doc
would help probably.

> Variable redeclaration option
> -----------------------------
>
>                 Key: JEXL-307
>                 URL: https://issues.apache.org/jira/browse/JEXL-307
>             Project: Commons JEXL
>          Issue Type: New Feature
>    Affects Versions: 3.1
>            Reporter: Dmitri Blinov
>            Assignee: Henri Biestro
>            Priority: Minor
>             Fix For: 3.2
>
>
> As of now, JEXL allows a script writer to redeclare a local variable during script evaluation.
> {code:java}
> var a = 1; var a = 2;{code}
> This may lead to potential errors with misspelled names and clashed variables. Checking
for already defined variable is a common feature of many languages. This feature can be implemented
in JEXL as an additional option of JexlFeatures class, enabled by default, thus allowing compatibility
with existing code.



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