Mixing generateStubs with java and xtend files

[dilyanpalauzov]

My understanding is that in .mwe2 files code { preferXtendStubs = } controls whether .java or .xtend files should be generated. If the destination .xtend or .java file exists, it is not overwritten, otherwise a stub file is created.

Sometimes some people think that some files should be in .java and others in .xtend, e.g. …serializer/SemanticSequencer.xtend and serializer/…SyntacticSequencer.java . The problem report is that in such cases it is not possible to prevent the generation of serializer/…SyntacticSequencer.xtend, if serializer/…SyntacticSequencer.java does exist. And if both files coexist at the end the compilation does not work. So:

• when generating stubs in Xtend, avoid creating files, if the same filename but with extension .java exists.
• when generating stubs in Java, avoid creating files, if the same filename but with extension .xtend exists.

[cdietrich]

i assume you can simply disable stub gen im the serializer = { generateStub = false }

[dilyanpalauzov]

Setting serializer = { generateStub = false } disables the generation of src-gen/…/serializer/Abstract…SemanticSequencer.java and src-gen/Abstract…SyntacticSequencer.java.

I do not know what the purpose of both Abstact classes is, or if they are needed in the concrete case. So I prefer to keep them, and just avoid re-generating serializer/…SemanticSequencer.xtend and serializer/…SyntacticSequencer.java

[LorenzoBettini]

Doesn't that section in the mwe2 file provide an option of the shape generateXtendStub = false? Other sections provide that. If not, we can add that.

[dilyanpalauzov]

I am referring to this example:

git clone https://github.com/openhab/openhab-core.git
cd openhab-core
mvn clean spotless:apply package -pl :org.openhab.core.model.thing

At https://github.com/openhab/openhab-core/tree/main/bundles/org.openhab.core.model.thing/src/org/openhab/core/model/thing can be seen GenerateThing.mwe2. The directory https://github.com/openhab/openhab-core/tree/main/bundles/org.openhab.core.model.thing/src/org/openhab/core/model/thing/serializer contains ThingSemanticSequencer.xtend, ThingSyntacticSequencer.xtend created by the Xtext generator, and ThingSyntacticSequencerExtension.java - actually used.

With this change:

index 3cbfcf08e..bdf6c97b0 100644
--- a/bundles/org.openhab.core.model.thing/src/org/openhab/core/model/thing/GenerateThing.mwe2
+++ b/bundles/org.openhab.core.model.thing/src/org/openhab/core/model/thing/GenerateThing.mwe2
@@ -51,7 +51,8 @@ Workflow {
       name = languageName
       fileExtensions = fileExtensions
       serializer = {
-        generateStub = generateXtendStub
+        generateStub = true
+        generateXtendStub = false
       }
     }
   }

serializer/ThingSyntacticSequencer.java and serializer/ThingSemanticSequencer.java are created, even when serializer/ThingSyntacticSequencer.xtend and serializer/ThingSemanticSequencer.xtend exist. The compilation fails with

[ERROR] bundles/org.openhab.core.model.thing/xtend-gen/org/openhab/core/model/thing/serializer/ThingSemanticSequencer.java:[16,14] The type ThingSemanticSequencer is already defined
[ERROR] bundles/org.openhab.core.model.thing/xtend-gen/org/openhab/core/model/thing/serializer/ThingSyntacticSequencer.java:[16,14] The type ThingSyntacticSequencer is already defined

because class ThingSemanticSequencer is defined in both bundles/org.openhab.core.model.thing/xtend-gen/org/openhab/core/model/thing/serializer/ThingSemanticSequencer.java and in bundles/org.openhab.core.model.thing/xtend-gen/org/openhab/core/model/thing/serializer/ThingSemanticSequencer.xtend.

So I want at the same time:

• have the src-gen/…/serializer/Abstract…SemanticSequencer.java and src-gen/Abstract…SyntacticSequencer.java files generated during the build process,
• have serializer/ThingSemanticSequencer.xtend, and
• have serializer/ThingSyntacticSequencer.java.

[LorenzoBettini]

Maybe I still don't understand but, just to be clear: if you want to switch from xtend stub to java stub, after changing the option in the mwe2, it's your responsibility to manually remove the previously generated xtend stub.

[dilyanpalauzov]

if you want to switch from xtend stub to java stub, after changing the option in the mwe2, it's your responsibility to manually remove the previously generated xtend stub.

Yes, but there are two stub files involved: SemanticSequencer and SyntacticSequencer. I want to have one of these files in java and the other in Xtend. According to my understanding, generateXtendStub mandates that either both files are in Xtend or both are in Java.

[LorenzoBettini]

I don't think that's supported. Either both xtend or both java.

[dilyanpalauzov]

Yes, this is what the current ticket is about: if Xtext wants to generate a stub file A.xtend, the file should not be created if A.java exists. Likewise, if Xtext wants to generate a file A.java and the file A.xtend exists, then A.java should not be created.