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https://issues.apache.org/jira/browse/JEXL-307?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16975645#comment-16975645
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Henri Biestro commented on JEXL-307:
------------------------------------
I may be missing your actual question but just because the lexical feature is
not equivalent to the lexical option.
Having seen many very heavy scripts (>2000 lines) and the most common source of
bugs, any _brand new_ solution using scripts should use the lexical feature and
"+lexical +lexicalShade -safe +strict" options IMHO.
The lexical feature throws a *parsing* exception when a variable is redeclared
whilst the lexical option throws exceptions at *execution* time (and that
option can be enabled/disabled at will through the jexl.options pragma). If
scripts are created before being used, the former fails at construction time -
and may prevent a whole app to start -, the latter at runtime - which may fail
some operation of that same app.
Considering any _existing_ solution using scripts, a smooth migration towards
using 3.2 safer scripting capabilities and the implied refactoring needs to be
achievable one script at a time; the current JEXL-307 implementation fits that
purpose.
(Production, migration, upgrade, support, legacy, resilience, stability...
burden vectors :))
> 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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