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From Benedikt Ritter <brit...@apache.org>
Subject Re: svn commit: r1649362 - /commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/
Date Sun, 04 Jan 2015 18:48:34 GMT
Hello Thomas,

2015-01-04 18:37 GMT+01:00 Thomas Neidhart <thomas.neidhart@gmail.com>:

> On 01/04/2015 06:07 PM, britter@apache.org wrote:
> > Author: britter
> > Date: Sun Jan  4 17:07:51 2015
> > New Revision: 1649362
> >
> > URL: http://svn.apache.org/r1649362
> > Log:
> > ScanlineFilter really is an interface
>
> there is usually a good reason to use an abstract class instead of an
> interface in case the type is public.
>

Yes, if the abstract class has some logic, which subclasses can leverage.
This was not the case here.


>
> This makes it possible to extend the interface even in minor interfaces.
>

I don't understand what you mean. Can you give an example?


>
> Maybe this is not necessary in this case, but should be kept in mind
> when doing such changes.
>

As long as an abstract class does not define logic, it doesn't make any
sense to define it as a class, rather than as an interface. Using
interfaces has an important advantage: you can only extend one class, but
can implement more than one interface. So we should really only define
abstract classes, if they have logic that justifies their existence.

Benedikt

P.S.: Nice to know, that someone is reviewing my commits in [imaging] :-)


>
> Thomas
>
> > Modified:
> >
>  commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilter.java
> >
>  commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterAverage.java
> >
>  commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterNone.java
> >
>  commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterPaeth.java
> >
>  commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterSub.java
> >
>  commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterUp.java
> >
> > Modified:
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilter.java
> > URL:
> http://svn.apache.org/viewvc/commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilter.java?rev=1649362&r1=1649361&r2=1649362&view=diff
> >
> ==============================================================================
> > ---
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilter.java
> (original)
> > +++
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilter.java
> Sun Jan  4 17:07:51 2015
> > @@ -20,7 +20,9 @@ import java.io.IOException;
> >
> >  import org.apache.commons.imaging.ImageReadException;
> >
> > -public abstract class ScanlineFilter {
> > -    public abstract void unfilter(byte[] src, byte[] dst, byte[] up)
> > +public interface ScanlineFilter {
> > +
> > +    void unfilter(byte[] src, byte[] dst, byte[] up)
> >              throws ImageReadException, IOException;
> > +
> >  }
> >
> > Modified:
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterAverage.java
> > URL:
> http://svn.apache.org/viewvc/commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterAverage.java?rev=1649362&r1=1649361&r2=1649362&view=diff
> >
> ==============================================================================
> > ---
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterAverage.java
> (original)
> > +++
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterAverage.java
> Sun Jan  4 17:07:51 2015
> > @@ -20,14 +20,13 @@ import java.io.IOException;
> >
> >  import org.apache.commons.imaging.ImageReadException;
> >
> > -public class ScanlineFilterAverage extends ScanlineFilter {
> > +public class ScanlineFilterAverage implements ScanlineFilter {
> >      private final int bytesPerPixel;
> >
> >      public ScanlineFilterAverage(final int bytesPerPixel) {
> >          this.bytesPerPixel = bytesPerPixel;
> >      }
> >
> > -    @Override
> >      public void unfilter(final byte[] src, final byte[] dst, final
> byte[] up)
> >              throws ImageReadException, IOException {
> >          for (int i = 0; i < src.length; i++) {
> >
> > Modified:
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterNone.java
> > URL:
> http://svn.apache.org/viewvc/commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterNone.java?rev=1649362&r1=1649361&r2=1649362&view=diff
> >
> ==============================================================================
> > ---
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterNone.java
> (original)
> > +++
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterNone.java
> Sun Jan  4 17:07:51 2015
> > @@ -20,8 +20,8 @@ import java.io.IOException;
> >
> >  import org.apache.commons.imaging.ImageReadException;
> >
> > -public class ScanlineFilterNone extends ScanlineFilter {
> > -    @Override
> > +public class ScanlineFilterNone implements ScanlineFilter {
> > +
> >      public void unfilter(final byte[] src, final byte[] dst, final
> byte[] up)
> >              throws ImageReadException, IOException {
> >          System.arraycopy(src, 0, dst, 0, src.length);
> >
> > Modified:
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterPaeth.java
> > URL:
> http://svn.apache.org/viewvc/commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterPaeth.java?rev=1649362&r1=1649361&r2=1649362&view=diff
> >
> ==============================================================================
> > ---
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterPaeth.java
> (original)
> > +++
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterPaeth.java
> Sun Jan  4 17:07:51 2015
> > @@ -20,7 +20,7 @@ import java.io.IOException;
> >
> >  import org.apache.commons.imaging.ImageReadException;
> >
> > -public class ScanlineFilterPaeth extends ScanlineFilter {
> > +public class ScanlineFilterPaeth implements ScanlineFilter {
> >      private final int bytesPerPixel;
> >
> >      public ScanlineFilterPaeth(final int bytesPerPixel) {
> > @@ -44,7 +44,6 @@ public class ScanlineFilterPaeth extends
> >          }
> >      }
> >
> > -    @Override
> >      public void unfilter(final byte[] src, final byte[] dst, final
> byte[] up)
> >              throws ImageReadException, IOException {
> >          for (int i = 0; i < src.length; i++) {
> >
> > Modified:
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterSub.java
> > URL:
> http://svn.apache.org/viewvc/commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterSub.java?rev=1649362&r1=1649361&r2=1649362&view=diff
> >
> ==============================================================================
> > ---
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterSub.java
> (original)
> > +++
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterSub.java
> Sun Jan  4 17:07:51 2015
> > @@ -20,14 +20,13 @@ import java.io.IOException;
> >
> >  import org.apache.commons.imaging.ImageReadException;
> >
> > -public class ScanlineFilterSub extends ScanlineFilter {
> > +public class ScanlineFilterSub implements ScanlineFilter {
> >      private final int bytesPerPixel;
> >
> >      public ScanlineFilterSub(final int bytesPerPixel) {
> >          this.bytesPerPixel = bytesPerPixel;
> >      }
> >
> > -    @Override
> >      public void unfilter(final byte[] src, final byte[] dst, final
> byte[] up)
> >              throws ImageReadException, IOException {
> >          for (int i = 0; i < src.length; i++) {
> >
> > Modified:
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterUp.java
> > URL:
> http://svn.apache.org/viewvc/commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterUp.java?rev=1649362&r1=1649361&r2=1649362&view=diff
> >
> ==============================================================================
> > ---
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterUp.java
> (original)
> > +++
> commons/proper/imaging/trunk/src/main/java/org/apache/commons/imaging/formats/png/scanlinefilters/ScanlineFilterUp.java
> Sun Jan  4 17:07:51 2015
> > @@ -20,8 +20,8 @@ import java.io.IOException;
> >
> >  import org.apache.commons.imaging.ImageReadException;
> >
> > -public class ScanlineFilterUp extends ScanlineFilter {
> > -    @Override
> > +public class ScanlineFilterUp implements ScanlineFilter {
> > +
> >      public void unfilter(final byte[] src, final byte[] dst, final
> byte[] up)
> >              throws ImageReadException, IOException {
> >          for (int i = 0; i < src.length; i++) {
> >
> >
>
>
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-- 
http://people.apache.org/~britter/
http://www.systemoutprintln.de/
http://twitter.com/BenediktRitter
http://github.com/britter

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