Thanks for the explanation. Looks like it would be helpful for IDE/static
analyzers/etc, without any impact for the users runtime.
I think a) makes sense, but b) would be OK too for me.
Cheers
Bruno
On Monday, 1 February 2021, 11:58:23 pm NZDT, Jochen Wiedmann
<jochen.wiedm...@gmail.com> wrote:
Hi,
as a followup to a discussion, that we had in August 2020, I'd like to
propose, that we introduce the @NonNull, and @Nullable annotations
into commons-lang.
Since that discussion, I began to gradually introduce those
annotations into my own code. From that, I have learned three things:
1.) Although those annotations have RetentionPolicy.RUNTIME, they are still
invisible at runtime. In particular, they do not impose any
runtime requirements.
We *can* use those annotations, but still remain a standalone library.
2.) There is no problem with mixed code: You can have some
classes, that use
those annotations, while others don't. Or, to rephrase that:
Even, if the ultimate
target should be, to use those annotations everywhere, they
can be introduced
gradually on a per-class base. We can have the target as a
long time goal, but
start small.
3.) Although the annotations aren't present in the compiled code,
they still provide
valuable information, if the source code is present in the
users IDE, because
the user can quickly jump into the respective file. (IDE
support could be enhanced,
for example Eclipse doesn't provide them as quick hints, but
that's something we
can work on.
Besides, static code analysis clearly *does* help (at least
in the current case) to
avoid errors. In my opinion, we are the ones, who are
setting the standards in good
code style, and this would clearly be an enhancement in that area).
So, assuming that my proposal should be accepted: How do we proceed? I
see two alternatives:
a) We had com.google.code.findbugs:jsr305:3.0.2 with a scope
"provided" to our dependencies. The scope will guarantee, that users
aren't affected at all.
b) We create our own annotations, say
org.apache.commons.lang3.annotations.NonNull, etc. When using
Spotbugs, or the respective IDE's, we need to adjust the namespace,
but that should be doable.
Personally, I'm in favour of using the javax.annotation namespace, thus a).
>From my experiences, I conclude that we should also do the following:
- Change ObjectUtils.defaultIfNull, and ObjectUtils.getIfNull to have
a @NonNull result,
because in practice, they are going to be used frequently. (In
cases, where the compiler
doesn't understand, that a value is, in fact, not nullable.)
- Convince the maintainers of the maven-compiler-plugin, that use of
those annotations
is something, that should be documented in the plugin configuration.
If that is given,
then IDE's might configure themselves automatically without the need
for IDE specific
files.
Jochen
1.)
--
Look, that's why there's rules, understand? So that you think before
you break 'em.
-- (Terry Pratchett, Thief of Time)
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