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https://issues.apache.org/jira/browse/JEXL-369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17532264#comment-17532264
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Dmitri Blinov commented on JEXL-369:
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Henri, could you please provide the vision of what should be changed with
introduction of let ? Are we adding nested block-scoped variables like in JS or
simply {{let}} is a new \{{var }} in lexical mode ?
May be this is not strictly relates to the ticket, but one of the things with
lexically scoped variables that I think we should consider is grammar change to
disallow single-statement variable declarations in lexical mode (as of now or
with let). For example {{if (cond1) var x = 0;}} If we look at other languages,
like JS or Java, this is not allowed. The statements where single-statement
variable declarations should be disallowed are {{if/else}}, {{{}while{}}},
{{{}do{}}}, {{{}for{}}}. For compatibility reasons in non-lexical mode we can
keep the existing grammar. If my work may be of any reference, here is what I
did. FunctionStatement() is named function declaration like {{function x() ...
}} and so I also restricted it in lexical mode.
{code:java}
void StatementBranch() #void : {}{ LOOKAHEAD(1) Block() |
LOOKAHEAD({!getFeatures().isLexical()}) GenericStatement() | Statement()}
void GenericStatement() #void : {}{ <SEMICOL> | AnnotatedStatement() |
LOOKAHEAD(FunctionStatementLookahead()) FunctionStatement() |
LOOKAHEAD(DeclareLocalVar()) VarStatement()
| LOOKAHEAD(Expression()) ExpressionStatement()
...
void Statement() #void : {}{ <SEMICOL> | AnnotatedStatement() |
| LOOKAHEAD(Expression()) ExpressionStatement()
...{code}
> Add 'let' and 'const' variable declarations
> -------------------------------------------
>
> Key: JEXL-369
> URL: https://issues.apache.org/jira/browse/JEXL-369
> Project: Commons JEXL
> Issue Type: Improvement
> Affects Versions: 3.2.1
> Reporter: Henri Biestro
> Assignee: Henri Biestro
> Priority: Major
> Fix For: 3.3
>
>
> WHAT:
> Add creation of lexical scope variables, modifiable with 'let',
> non-modifiable through 'const'.
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