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From "Dmitri Blinov (Jira)" <j...@apache.org>
Subject [jira] [Commented] (JEXL-307) Variable redeclaration option
Date Sat, 02 Nov 2019 13:35:00 GMT

    [ https://issues.apache.org/jira/browse/JEXL-307?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16965368#comment-16965368
] 

Dmitri Blinov commented on JEXL-307:
------------------------------------

Things are getting a little bit tricky. Can we ensure that the following test passes ?
{code:java}
    @Test
    public void testLexical5() throws Exception {
        JexlEngine jexl = new JexlBuilder().strict(true).create();
        JexlEvalContext ctxt = new JexlEvalContext();
        JexlOptions options = ctxt.getEngineOptions();
        // ensure errors will throw
        options.setLexical(true);
        JexlScript script;
        Object result;        script = jexl.createScript("var x = 42; var y = () -> { {var
x = 0}; return x; }; y()");
        try {
        result = script.execute(ctxt);
            Assert.assertEquals(42, result);
            Assert.fail();
        } catch (JexlException xany) {
            String ww = xany.toString();
        }
    }
 {code}

Maybe we can refactor the hoisted variables from local to contextual variables that shadow
original evaluation context?

> 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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