8000 Revert `@static` annotation by gkossakowski · Pull Request #1340 · scala/scala · GitHub
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Revert @static annotation #1340

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Merged
merged 8 commits into from
Sep 18, 2012
Merged

Revert @static annotation #1340

merged 8 commits into from
Sep 18, 2012

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gkossakowski
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This pull request reverts all changes related to @static feature.

As it has been discussed on scala-internals this feature should come with SIP in the first place. We need much more time hash out the details of @static semantics which we don't have at the moment given how close the RC1 is.

Review by @axel22.

@gkossakowski
Revert "Fix SI-6294."
10c9cf0 
This reverts commit cb393fc.

Conflicts:

	src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
@gkossakowski
Revert "Fix SI-4581."
4ed7a60 
This reverts commit 373f22a.
@gkossakowski
Revert "Fixes SI-6236."
6854842 
This reverts commit faa114e.
@gkossakowski
Revert "Fixes SI-6189."
6b9e1a0 
This reverts commit 5a8dfad.

Conflicts:

	src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
@gkossakowski
Revert "WIP add private/lazy checks and a few tests."
585069c 
This reverts commit 2272390.
@gkossakowski
Revert "Implement @static annotation on singleton object fields."
4bfcada 
This reverts commit 892ee3d with
exception of keeping `@static` annotation in the library so we
can deploy a new starr that does not depend on it before removing
it completely.

Conflicts:

	src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
	src/compiler/scala/tools/nsc/backend/jvm/GenJVM.scala
	src/compiler/scala/tools/nsc/transform/CleanUp.scala
@gkossakowski
New starr that does not depend on @static.
220ea07 
Deployed a new starr that does not depend on `@static` annotation.
The next step will be deleting `@static` from the library
altogether.
@gkossakowski
Remove @static annotation from the library.
fbed813 
It's a follow-up commit on 4bfcada.
@axel22
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axel22 commented Sep 18, 2012

LGTM

@scala-jenkins
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Started jenkins job pr-rangepos at https://scala-webapps.epfl.ch/jenkins/job/pr-rangepos/499/

@scala-jenkins
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Started jenkins job pr-scala-testsuite-linux-opt at https://scala-webapps.epfl.ch/jenkins/job/pr-scala-testsuite-linux-opt/1207/

@scala-jenkins
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jenkins job pr-rangepos: Success - https://scala-webapps.epfl.ch/jenkins/job/pr-rangepos/499/

@scala-jenkins
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jenkins job pr-scala-testsuite-linux-opt: Success - https://scala-webapps.epfl.ch/jenkins/job/pr-scala-testsuite-linux-opt/1207/

gkossakowski added a commit that referenced this pull request Sep 18, 2012
@gkossakowski
Merge pull request #1340 from gkossakowski/revert-static-annotation
a9f95dc 
Revert `@static` annotation
@gkossakowski gkossakowski merged commit a9f95dc into scala:2.10.x Sep 18, 2012
@allxiao
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allxiao commented May 29, 2015

Hi, is there any further plan for this @static feature? It's been nearly 3 years since the reversion.

@lrytz
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lrytz commented May 29, 2015

There's been a more recent discussion here: https://groups.google.com/forum/#!searchin/scala-internals/static$20annotation/scala-internals/Y3OlFWPvnyM/tGE5BQw4Pe0J

@lrytz
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lrytz commented May 29, 2015

the issues discussed there are blockers imo.

This was referenced Apr 7, 2017
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@2xsaiko
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2xsaiko commented Apr 17, 2017

Did anything else ever happen after this discussion?

@jvican
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jvican commented Apr 17, 2017 •
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Yes @mrebhan. A SIP was created: http://docs.scala-lang.org/sips/pending/static-members.html. The SIP is under implementation since a member of the SIP board volunteered to provide one.

This implementation would in theory target 2.12.x.

@SethTisue
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yes, see http://docs.scala-lang.org/sips/pending/static-members.html

plus it was discussed at a SIP meeting. ordinarily the minutes would be found at http://docs.scala-lang.org/sips/minutes-list.html, but I see that's fallen behind by some months — for now see scala/docs.scala-lang#762

@jvican
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jvican commented Apr 17, 2017

I beat you by 1 minute and 37 seconds @SethTisue. You're not as fast as you used to be 😜.

@SethTisue
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I spent the extra two minutes finding the minutes PR :-P :-P

@2xsaiko
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2xsaiko commented Apr 17, 2017

Thanks guys :'D

@Clyybber
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Any progress on this feature?

@NthPortal
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As of 2.13.0/2.12.9/2.11.12 (the latest versions of each of the last three releases), Scala generates static forwarder methods:

// Test.scala
object Test {
  val foo: String = "foo"
  def bar: String = "bar"
}
// javap -c 'Test.class' # compiled with 2.13.0, 2.12.9 or 2.11.12
public final class Test {
  public static java.lang.String bar();
    Code:
       0: getstatic     #16                 // Field Test$.MODULE$:LTest$;
       3: invokevirtual #18                 // Method Test$.bar:()Ljava/lang/String;
       6: areturn

  public static java.lang.String foo();
    Code:
       0: getstatic     #16                 // Field Test$.MODULE$:LTest$;
       3: invokevirtual #21                 // Method Test$.foo:()Ljava/lang/String;
       6: areturn
}
// javap -c -p 'Test$.class' # compiled with 2.13.0
public final class Test$ {
  public static final Test$ MODULE$;

  private static final java.lang.String foo;

  public static {};
    Code:
       0: new           #2                  // class Test$
       3: dup
       4: invokespecial #14                 // Method "<init>":()V
       7: putstatic     #16                 // Field MODULE$:LTest$;
      10: ldc           #17                 // String foo
      12: putstatic     #19                 // Field foo:Ljava/lang/String;
      15: return

  public java.lang.String foo();
    Code:
       0: getstatic     #19                 // Field foo:Ljava/lang/String;
       3: areturn

  public java.lang.String bar();
    Code:
       0: ldc           #23                 // String bar
       2: areturn

  private Test$();
    Code:
       0: aload_0
       1: invokespecial #24                 // Method java/lang/Object."<init>":()V
       4: return
}
// javap -c -p 'Test$.class' # compiled with 2.12.9
public final class Test$ {
  public static Test$ MODULE$;

  private final java.lang.String foo;

  public static {};
    Code:
       0: new           #2                  // class Test$
       3: invokespecial #14                 // Method "<init>":()V
       6: return

  public java.lang.String foo();
    Code:
       0: aload_0
       1: getfield      #17                 // Field foo:Ljava/lang/String;
       4: areturn

  public java.lang.String bar();
    Code:
       0: ldc           #20                 // String bar
       2: areturn

  private Test$();
    Code:
       0: aload_0
       1: invokespecial #21                 // Method java/lang/Object."<init>":()V
       4: aload_0
       5: putstatic     #23                 // Field MODULE$:LTest$;
       8: aload_0
       9: ldc           #24                 // String foo
      11: putfield      #17                 // Field foo:Ljava/lang/String;
      14: return
}
// javap -c -p 'Test$.class' # compiled with 2.11.12
public final class Test$ {
  public static final Test$ MODULE$;

  private final java.lang.String foo;

  public static {};
    Code:
       0: new           #2                  // class Test$
       3: invokespecial #12                 // Method "<init>":()V
       6: return

  public java.lang.String foo();
    Code:
       0: aload_0
       1: getfield      #17                 // Field foo:Ljava/lang/String;
       4: areturn

  public java.lang.String bar();
    Code:
       0: ldc           #20                 // String bar
       2: areturn

  private Test$();
    Code:
       0: aload_0
       1: invokespecial #21                 // Method java/lang/Object."<init>":()V
       4: aload_0
       5: putstatic     #23                 // Field MODULE$:LTest$;
       8: aload_0
       9: ldc           #24                 // String foo
      11: putfield      #17                 // Field foo:Ljava/lang/String;
      14: return
}

lrytz pushed a commit to lrytz/scala that referenced this pull request Nov 5, 2019
Abstract over dependency context in Compile
79617a0 
This commit completes the abstraction over dependency kinds in the
incremental compiler, started with scala#1340.

Rewritten from sbt/zinc@649168e
@HyukjinKwon
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Scala 2.13 is out. How do we plan this?

@NthPortal
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it's not obvious to me that there's still a need for this. given that the compiler already generates forwarders, what's your use case @HyukjinKwon?

@HyukjinKwon
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I would like to define an object that has a static field that can be accessed in Java as well, for example:

object Foo {
  val field = "abc"
}

and in Java side:

Foo.field

The reason is that to provide the consistent API usages in both Scala and Java. Does it make snese?

@NthPortal
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as I mentioned, the compiler generates static forwarders that can be accessed from Java. please see the bytecode showing the static methods in my comment immediately above. while they are methods rather than fields, they still permit access from Java (and are generally considered better practice anyway).

@HyukjinKwon
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HyukjinKwon commented Sep 23, 2020 •
edited
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The point here is to have a field instead of a method in Java side in order to support the same shape of the APIs. I want to support Foo.field in both Java and Scala instead of Foo.field() in Java alone.

Just allowing a way to access is not enough in particular in APIs. For example, you cannot do such things:

object Nations {
  object Korea {
    def localize = ...  
  }
  val korea = Korea

  object US {
    def localize = ...      
  }
  val us = US
}

In Scala:

Nations.us.localize(...)

In Java:

Nations.us().localize(...)

@NthPortal
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that's part of the Uniform Access Principle - that is, it allows you to swap a val for a def with no parameter lists and vice versa in a binary and source compatible way. while it will look different in Java, because they both are methods and use (), they remain source compatible when you change the implementation.

@HyukjinKwon
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So just to clarify, there's no way to make Java to call Nations.us.localize(...) like Scala does, and this reverted change fixed it. Is it correct?

@dwijnand
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Correct, there's no way to define a static field in Scala. The proposal for that is SIP-30 (https://docs.scala-lang.org/sips/static-members.html) and it's "under review" but hasn't been discussed recently. I think it lacks both a motivated implementer and a SIP committee champion, at this point.

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