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Re: [cross-project-issues-dev] org.eclipse.equinox.common has added generics to API in org.eclipse.core.runtime package

My advice is to go with the explicit version where one has to add the @SuppressWarnings("unchecked").

Dani



From:        Markus Keller/Zurich/IBM@IBMCH
To:        Cross project issues <cross-project-issues-dev@xxxxxxxxxxx>, "General development mailing list of the Eclipse project." <eclipse-dev@xxxxxxxxxxx>
Date:        20.02.2015 18:23
Subject:        Re: [cross-project-issues-dev] org.eclipse.equinox.common has added generics to API in org.eclipse.core.runtime package
Sent by:        cross-project-issues-dev-bounces@xxxxxxxxxxx




Yeah, this basically hides the unsafe cast in the implementation of Class#cast(..). It has its advantages and disadvantages:

Pro: Performs an additional dynamic Class#isInstance(..) check that throws a CCE at the place where the unsafe cast happens => fail-fast is good (although the cast at the caller side also won't be far away; and that's how it used to work in the past).


Contra: Is less explicit than the SuppressWarnings version, since the type safety problem is not immediately visible at the code location where the unchecked cast happens.


=> adapter.cast(..) is OK for me, but not a must.


Markus




From:        
"Andrey Loskutov" <loskutov@xxxxxx>
To:        
cross-project-issues-dev@xxxxxxxxxxx
Cc:        
"General development mailing list of the Eclipse project." <eclipse-dev@xxxxxxxxxxx>, Cross project issues <cross-project-issues-dev@xxxxxxxxxxx>
Date:        
2015-02-20 15:35
Subject:        
Re: [cross-project-issues-dev] org.eclipse.equinox.common has added generics to API in org.eclipse.core.runtime package
Sent by:        
cross-project-issues-dev-bounces@xxxxxxxxxxx




Hi,

Before everyone starts to change getAdapter() implementation, please consider to user warning-free alternative:

 
Instead of writing:

 
       @SuppressWarnings("unchecked")
      public <T> T getAdapter(Class<T> adapter) {
              if (ICompilationUnit.class.equals(adapter))
                      return (T) getCompilationUnit();
              return null;
      }

 
use Class.cast() API:


      public <T> T getAdapter(Class<T> adapter) {
              if (ICompilationUnit.class.equals(adapter))
                      return adapter.cast(getCompilationUnit());
              return null;
      }

 
Kind regards,
Andrey Loskutov

http://google.com/+AndreyLoskutov
 
 
Gesendet:
Freitag, 20. Februar 2015 um 15:21 Uhr
Von:
"Thomas Watson" <tjwatson@xxxxxxxxxx>
An:
"Cross project issues" <cross-project-issues-dev@xxxxxxxxxxx>, "General development mailing list of the Eclipse project." <eclipse-dev@xxxxxxxxxxx>
Betreff:
[cross-project-issues-dev] org.eclipse.equinox.common has added generics to API in org.eclipse.core.runtime package

See
https://bugs.eclipse.org/bugs/show_bug.cgi?id=442021

Markus Keller wrote up an nice summary of what consumers should do to fix any warnings that may be caused by this change at
https://bugs.eclipse.org/bugs/show_bug.cgi?id=442021#c25

Here is a copy of the recommendations if you are going to compile against the latest version of org.eclipse.equinox.common:

1. In MANIFEST.MF, update your Require-Bundle:  org.eclipse.core.runtime;bundle-version="[3.11.0,4.0.0)", or org.eclipse.equinox.common;bundle-version="[3.7.0,4.0.0)", or update your Import-Package: org.eclipse.core.runtime; version="[3.5,4.0)"

2. If your bundle re-exports one of these bundles, then you also have to make sure the minor version is incremented.

3. Remove unnecessary casts (Clean Up, or Problems view > Quick Fix > Select All)

4. Update implementations of IAdaptable#getAdapter(Class<T>), unless you override another implementation of that method that still uses the old signature.

Typical change:
Old:
      public Object getAdapter(Class adapter) {
              if (ICompilationUnit.class.equals(adapter))
                      return getCompilationUnit();
              return null;
      }

New:
      @SuppressWarnings("unchecked")
      public <T> T getAdapter(Class<T> adapter) {
              if (ICompilationUnit.class.equals(adapter))
                      return (T) getCompilationUnit();
              return null;
      }

5. Update implementations of IAdapterFactory

Hint for 4. & 5.:
- Open Type Hierarchy on IAdaptable, etc.
- In the view menu, select a working set that contains your projects
- In the methods list of the Type Hierarchy view, select the methods, and then click the first toolbar button (Lock View and Show Members in Hierarchy)



Tom


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