Garret Wilson created JEXL-342:
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Summary: 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
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").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> getBar(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outdated style and less safe API just to get JEXL to work.
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