[jira] [Commented] (JEXL-342) Support for Java Optional.

["Henri Biestro (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JEXL-342?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17364888#comment-17364888 ] 

Henri Biestro commented on JEXL-342:
------------------------------------

Dmitri, improvements on the base code line can be made and proposed as long as they don't break compatibility and simple language philosophy. Forking was probably the right move for your use case.

Anyhow, there are many ways to extend JEXL that don't require changing its code base and this feature, supporting Optional<?> in some meaningful way, is one of them.
If you look at https://github.com/apache/commons-jexl/commit/f4903cf1df0a144f61073af038806b7ae8d4f8c0 , you'll find a baseline for the described feature. It also supports automatic Reference and AtomicReference dereferencing.
Garret, hoping you'll find it useful; feel free to push PRs on this code to help test and stabilise the behaviour.



> Support for Java Optional.
> --------------------------
>
>                 Key: JEXL-342
>                 URL: https://issues.apache.org/jira/browse/JEXL-342
>             Project: Commons JEXL
>          Issue Type: New Feature
>    Affects Versions: 3.1
>            Reporter: Garret Wilson
>            Priority: Major
>             Fix For: Later
>
>
> Does JEXL provide any native support for Java 8+ {{Optional<>}}? If not can this this easily be added as some sort of plugin, or better yet can it be added to the library?
> h3. {{Optional}} Traversal
> I need to create an API that works well for application developers as for those using templates with JEXL expressions. Let's say that the {{Bar}} class has a {{Bar.getName()}}. And the {{Foo}} class has this method:
> {code:java}
> Optional<Bar> getBar(String barId);
> {code}
> In code getting the "test" foo-bar name would be like this:
> {code:java}
> String fooBarName=foo.getBar("test").map(Bar::getName).orElse(null);
> {code}
> I want the navigation across {{Optional<>}} to work just as if it were a nullable variable. That is, I want the following JEXL expression to give the same result as {{fooBarName}} above:
> {code}
> foo.bar("test").name
> {code}
> If {{Foo.getBar(String)}} returned a nullable rather than an {{Optional<>}}, I think JEXL would work for this already. but the whole point of {{Optional<>}} is that I keep nullables out of my code, so I don't want to create inferior APIs inconsistent with the rest of my project just to work with JEXL.
> h3. {{Optional}} Getter Name
> As icing on the cake, I would like to have {{Optional<>}} returning getter discovery to recognize the {{findXXX}} pattern, as [Stephen Colebourne suggested|https://blog.joda.org/2015/09/naming-optional-query-methods.html]. I've been using this pattern for several years, and I really like it. Thus to indicate that the {{Foo.getBar(String)}} "getter" doesn't return a nullable but an {{Optional<>}}, I would name it {{Foo.findBar(String)}}, like this:
> {code:java}
> Optional<Bar> findBar(String barId);
> {code}
> I would thus want the exact same JEXL expression above to still work:
> {code}
> foo.bar("test").name
> {code}
> Otherwise I'll have to forego use of modern Java constructs and make an outdated style and less safe API just to get JEXL to work.



--
This message was sent by Atlassian Jira
(v8.3.4#803005)