The bug that I'm currently dealing with requires me to replace implements with extends upon selection of the associated quick fix.
For example:
public class R{
}
class Q implements R{ //error here
}
The quick fix will be to change implements to extends (That's what I am focusing on). But to do this I need to have TypeDeclaration.SUPERCLASS_TYPE as a ChildListPropertyDiscriptor whereas it's now a ChildPropertyDiscriptor. Which makes it unable to be supplied as a parameter to getListRewrite.
I want to know if there is any way I can make TypeDeclaration.SUPERCLASS_TYPE as a ChildListPropertyDiscriptor. Or else some other way exists to do this.
My full code snippet is the following:
TypeDeclaration typeDecl= (TypeDeclaration) selectedNode.getParent();
{
ASTRewrite rewrite= ASTRewrite.create(root.getAST());
ASTNode placeHolder= rewrite.createMoveTarget(selectedNode);
ListRewrite interfaces= rewrite.getListRewrite(typeDecl, TypeDeclaration.SUPERCLASS_TYPE_PROPERTY); //problem here
interfaces.insertFirst(placeHolder, null);
String label= CorrectionMessages.LocalCorrectionsSubProcessor_implementstoextends_description;
Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.CHANGE_EXTENDS_TO_IMPLEMENTS, image);
proposals.add(proposal);
}
Java does not support multi-inheritance so there is only one type for extends supported. This explains why TypeDeclaration.SUPERCLASS_TYPE is no list and so has no ChildListPropertyDescriptior (for possible use with ListRewrite).
What you want instead is ASTRewrite.set():
rewrite.set(typeDecl, TypeDeclaration.SUPERCLASS_TYPE_PROPERTY, placeHolder, null);
Related
Dart allows to use the standard library names for conditional import/export, like this:
export 'src/hw_none.dart' // Stub implementation
if (dart.library.io) 'src/hw_io.dart' // dart:io implementation
if (dart.library.html) 'src/hw_html.dart'; // dart:html implementation
Is it possible to define a custom property/condition? For example, pass it when compiling.
I have a project that I would like to split into two variants: Flutter variant and pure Dart variant. The choice of the variant depends at compile time, and the necessary implements of abstract classes defines at compile time.
Custom properties where an experimental feature in Dart 1. With Dart 2 there is no longer any support for user defined custom conditions in compile time.
Here is the discussion referencing your question.
All you can do is, switch between implementations on run time:
abstract class SomeFactory {
String get message;
factory SomeFactory() {
if(Platform.environment['SOME_VAR'] != null)
return new _SomeImplementation();
return new _SomeOtherImplementation();
}
}
class _SomeImplementation implements SomeFactory {
#override
String get message => 'SomeImplementation';
}
class _SomeOtherImplementation implements SomeFactory {
#override
String get message => "OtherImplementation";
}
Check this blog entry for more details.
I try to extend my MyDSLProposalProvider from an external Eclipse RCP Project. I created an extension point schema which requires a class property which extends my ProposalProvider. In the new project I extend the class an overrode some methods justs to give me some output so I can see that the external method is called. But this is currently not happening. Is there anything I have to consider?
Currently the hirachy looks like:
MyDSLProposalProvider extends AbstractMyDSLProposalProvider
ExternalProposalProvider extends MyDSLProposalProvider
I rewrote a Method generated in the AbstractMyDSLProposalProvider but when its triggered the predefined Method in the AbstractMyDSLProposalProvider is called and not my new implementation.
public class ExternalMyDSLProposalPovider extends MyDSLProposalProvider
{
#Override
public void completeComponent_Name(EObject model, Assignment
assignment, ContentAssistContext context,
ICompletionProposalAcceptor acceptor) {
System.err.println("extern");
if(model instanceof Component)
{
createProposal("foo", "foo", context, acceptor);
}
super.completeComponent_Name(model, assignment, context, acceptor);
}
}
This is the class in the external Eclipse Project.
Thanks for the help.
When you declare an extension point using a schema that you have defined Eclipse puts that declaration in the extension point registry. That is all that is does, you must then write code to make uses of those declarations.
You read the extension point registry using something like:
IExtensionRegistry extRegistry = Platform.getExtensionRegistry();
IExtensionPoint extPoint = extRegistry.getExtensionPoint("your extension point id");
IConfigurationElement [] elements = extPoint.getConfigurationElements();
elements is now an array of the declarations in the various plugins using the extension point.
IConfigurationElement has various methods to get the values of the attributes of the declaration.
If you have defined a class in one of the attributes you can create an instance of the class using:
IConfigurationElement element = .... a config element
Object obj = element.createExecutableExtension("attribute name");
In your case the result should be your ExternalMyDSLProposalPovider.
You will then need to hook this object up with whatever is doing to proposals.
I'm trying to extend a class (SWT.java) from a Java library (SWT) that only has static final members. An excerpt from the library class:
package org.eclipse.swt;
import org.eclipse.swt.internal.*;
public class SWT {
public static final int None = 0;
// ...
public static final int MouseDown = 3;
// ...
}
My Java wrapper class that worked fine in Java land:
public class SWT extends org.eclipse.swt.SWT {
public static final int FinalizeText = 201;
public static final int ParseText = 202;
}
Now if I try to use my new SWT class in Scala, I'll get errors like this:
Error:(198, 27) value MouseDown is not a member of object my.package.SWT
table.addListener(SWT.MouseDown, periodEditListener)
^
Ideally I would like a new SWT object with which I could access both original members (e.g. MouseDown) and members I define (e.g. FinalizeText).
It seems that Scala interprets everything useful about this class as an object, which is fine if we just want to use the original SWT definitions, but you can't easily extend objects in Scala.
It has occurred to me that implicits a la pimp my library might be the way to go, but even were I to get this to work, I think the solution would not be accessible from Java (still, I have not even gotten in to work in Scala).
How to best tackle the problem? Maybe the right answer is to just define a separate, unrelated object.
I don't think there is a good way to do what you want such that:
You can neatly tie all members to an identifier (i.e. refer to the field via SWT.X instead of X)
Have it work both in Scala and Java.
You don't have to manually forward fields.
This is a documented limitation of Scala -- see access java base class's static member in scala.
In addition, I don't think the implicit route works either, because you can't treat a Java class as a value: How to access a Java static method from Scala given a type alias for that class it resides in
Probably the best way to do what you want is to manually forward the static members you need in my.package.SWT:
public class SWT extends org.eclipse.swt.SWT {
public static final int FinalizeText = 201;
public static final int ParseText = 202;
public static int getMouseDown() {
return MouseDown;
}
}
If you only care about automatically forwarding members and not about the other requirements, you can use import:
import org.eclipse.swt.SWT._
table.addListener(MouseDown, periodEditListener)
I am accepting yuzeh's answer for thoroughness, general applicability, and helpfulness, but here is what I actually did, which is slightly different:
I was very tempted by yuzeh's last suggestion for the sake of uniformity, i.e.
import org.eclipse.swt.SWT._
import my.package.SWT._
Although as my first example snippet above inadvertently shows, SWT.None unfortunately is, so bringing it into the local namespace would conflict with Option's None.
I think for now I'll just import like:
import org.eclipse.swt.SWT
import my.package.{SWT => MySWT}
If nothing else, it is a bit more clear where the constants are coming from. There, I talked myself into believing this is better :).
I have a bunch of data entities that all implement Entity. Now I want to expose some of these entities to JavaScript code, but I can't just make a bunch of JavaScriptObject subclasses because of the one-implementation rule.
So, I'm using this kind of thing:
public class JsStandardScale3 implements StandardScale3 {
private JavaScriptObject wrapped;
public JsStandardScale3(JavaScriptObject wrapped) {
this.wrapped = wrapped;
}
#Override
public native Long getLicenseId() /*-{
this.#com.activegrade.client.exported.JsStandardScale3::wrapped.getLicenseId();
}-*/;
This works, it's just a lot of work. The overlay type structure is so much nicer. Any suggestions?
It turns out that you CAN extend JavaScriptObject with multiple subclasses of an interface as long as all of your extensions are from a single "root" extension of JSO.
For example, I have the structure Standard extends Entity and Course extends Entity. I could NOT do:
JsStandard extends JavaScriptObject...
JsCourse extends JavaScriptObject...
but I could do:
JsEntity extends JavaScriptObject...
JsStandard extends JsEntity...
JsCourse extends JsEntity...
fantastic!
The only limitation is that every method must be marked final, which works fine for a simple overlay scenario.
While creating classes using Generators, it's possible to discover all subclasses of a type. You can find this technique for example in the GWT Showcase source (see full code):
JClassType cwType = null;
try {
cwType = context.getTypeOracle().getType(ContentWidget.class.getName());
} catch (NotFoundException e) {
logger.log(TreeLogger.ERROR, "Cannot find ContentWidget class", e);
throw new UnableToCompleteException();
}
JClassType[] types = cwType.getSubtypes();
I would like to do something similar, but instead of extending a class (or implementing an interface)
public class SomeWidget extends ContentWidget { ... }
, could I also do this by annotating Widgets?
#MyAnnotation(...)
public class SomeWidget extends Widget { ... }
And then finding all Widgets that are annotated with #MyAnnotation? I couldn't find a method like JAnnotationType.getAnnotatedTypes(), but maybe I'm just blind?
Note: I was able to make it work with the Google Reflections library, using reflections.getTypesAnnotatedWith(SomeAnnotation.class), but I'd prefer using the GeneratorContext instead, especially because this works a lot better when reloading the app in DevMode.
Yes - easiest way is to iterate through all types, and check them for the annotation. You might have other rules too (is public, is non-abstract) that should also be done at that time.
for (JClassType type : oracle.getTypes()) {
MyAnnotation annotation = type.getAnnotation(MyAnnotation.class);
if (annotation != null && ...) {
// handle this type
}
}
The TypeOracle instance can be obtained from the GeneratorContext using context.getTypeOracle().
Note that this will only give you access to types on the source path. That is, only types currently available based on the modules being inherited and <source> tags in use.