GitHub user HyukjinKwon opened a pull request:
https://github.com/apache/spark/pull/14490
[SPARK-16877][BUILD] Add rules for preventing to use Java annotations
(Deprecated and Override)
## What changes were proposed in this pull request?
This PR adds both rules for preventing to use `@Deprecated` and `@Override`.
- Java's `@Override`
It seems Scala compiler just ignores this. This can be problematic when
traits or abstract classes as inherited. Scala compiles seems `override`
modifier is only mandatory for " that override some other **concrete member
definition** in a parent class" but not for for **incomplete member
definition** (such as ones from trait or abstract), see
(http://www.scala-lang.org/files/archive/spec/2.11/05-classes-and-objects.html#override)
For a simple example,
- Normal class - needs `override` modifier
```bash
scala> class A { def say = {}}
defined class A
scala> class B extends A { def say = {}}
<console>:8: error: overriding method say in class A of type => Unit;
method say needs `override' modifier
class B extends A { def say = {}}
^
```
- Trait - does not need `override` modifier
```bash
scala> trait A { def say }
defined trait A
scala> class B extends A { def say = {}}
defined class B
```
To cut this short, in the latter case, we can write `@Override`
annotation (meaning nothing) which might confuse engineers that Java's
annotation is working fine. It might be great if we prevent those potential
confusion.
- Java's `@Deprecated`
When `@Deprecated` is used, it seems Scala compiler recognises this
correctly but it seems we use Scala one `@deprecated` across codebase.
## How was this patch tested?
Manually tested, by inserting both `@Override` and `@Deprecated`. This will
shows the error messages as below:
```bash
Scalastyle checks failed at following occurrences:
[error] ... : @deprecated should be used instead of @java.lang.
```
```basg
Scalastyle checks failed at following occurrences:
[error] ... : override modifier should be used instead of
@java.lang.Override.
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/HyukjinKwon/spark SPARK-16877
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/14490.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #14490
----
commit 79eaef7f55779e949d7e8dc0b4e4749d76f99c9f
Author: hyukjinkwon <[email protected]>
Date: 2016-08-04T02:02:25Z
Add rules for preventing to use Java annotations (Deprecated and Override)
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