Re: [eclipse-dev] [cross-project-issues-dev] org.eclipse.equinox.common

[Markus Keller <markus_keller@xxxxxxxxxx>]

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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