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From "Dmitri Blinov (JIRA)" <j...@apache.org>
Subject [jira] [Created] (JEXL-250) Safe navigation operator
Date Wed, 24 Jan 2018 13:58:00 GMT
Dmitri Blinov created JEXL-250:
----------------------------------

             Summary: Safe navigation operator
                 Key: JEXL-250
                 URL: https://issues.apache.org/jira/browse/JEXL-250
             Project: Commons JEXL
          Issue Type: New Feature
    Affects Versions: 3.1
            Reporter: Dmitri Blinov


It would be more convenient for a script writer to have a kind of safe navigation operator,
in the form of, for example, ({{object?.property),}} for null pointer dereferences. I think
its quite a common feature of many scripting (and compiled languages) now. The safe operator
should work like basic navigation operator for non null values and should short-circuit the
entire expression evaluation after encountering null value.

I see the difference of new operator from the existing lenient mode evaluation in ability
to explicitly define places in an expression where {{null}} deference is allowed, for example
the expression {code}Order.Customer?.Name{code} defines that each {{Order}} should have a
{{Customer}} and only the {{Name}} of the {{Customer}} is optional.

The difference of new operator from the existing null coalescing {{??}} operator is in its
ability to short-circuit evaluation.

So, safe navigation operator would be a helpful syntaxic sugar which in my opinion does not
overlap with an existing functionality.




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