Hi Hector, all,
I think of the Lookup API as a great tool to extend the capabilities of
classes _without_ using inheritance.
Once your classes implement the "Lookup.Provider" interface you can
return Elephant.class, CupOfTea.class and even Beer.class
implementations from your getLookup() _without_ altering your API.
This is the biggest problem I see with the PR: you want to add a new
feature to the Lookup.class (the Optional support) using inheritance,
and not using the Lookup API itself. That's weird for me.
You could always create a NetBeans module with an Optional-aware
(Stream-aware too?) "LookupOptional" interface in the API, a simple
implementation and then register the interface in the META-INF/services
(@Service) of the module as we always do.
Once a dependency on this module is ready one could write:
----
Lookup lookup = ...
LookupOptional lookupOptional = lookup.lookup(LookupOptional.class);
Whatever w = lookupOptional.lookup(lookup, Whatever.class).orElse(...)
----
If creating a new module for this Optional (Streamy?) features is too
much of an effort then, as an alternative, I'd suggest adding a new
method to org.openide.util.lookup.Lookups like so:
----
public static <T> Optional<T> of(Lookup lookup, Class<T> clazz) {
return Optional.ofNullable(lookup.lookup(clazz));
}
----
So one could write:
----
Lookup lookup = ...
Whatever x = Lookups.of(lookup, Whatever.class).orElse(...)
----
I think that the first approach is cleaner as it does not touch the
Lookup API at all, and keeps backwards compatibility.
Kind regards,
Antonio
P.S.: As a curiosity: I'm afraid I'm on the Optional-dislikers group, so
if you finally propose a "LookupOptional" interface in a new module I'm
afraid I won't be using it myself.
[1]
https://bits.netbeans.org/dev/javadoc/org-openide-util-lookup/org/openide/util/lookup/Lookups.html
El 2/7/20 a las 18:32, Hector Espert escribió:
A few months ago, I created a draft PR to add a method in the Lookup class
that returns a Java optional.
https://github.com/apache/netbeans/pull/2063
There wasn't any special reason. Only I used it to study how the Netbeans
documentation works.
If anybody is interested in that, I will continue with the development. If
not, I will close the PR.
Regards, Hector
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