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https://issues.apache.org/jira/browse/LANG-637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13462087#comment-13462087
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Matt Benson commented on LANG-637:
----------------------------------
Again, from the usage standpoint I just envisioned that if I were getting diffs
I might for some reason want to know at a code level precisely _in what manner_
two objects differed. You are of course correct that ultimately the retrieval
mechanism could really only be object-based, though we could do some generics
tricks in that regard. What about something like:
{code}
public abstract class Diff<T> extends oacl.tuple.Pair<T, T> {
private final Type type;
private final String fieldName;
protected Diff(String fieldName) {
this.type =
ObjectUtils.defaultIfNull(TypeUtils.getTypeArguments(getClass(),
Diff.class).get(Diff.class.getTypeParameters()[0]), Object.class);
}
public final Type getType() {
return type;
}
public final String getFieldName() {
return fieldName;
}
}
{code}
{code}
public class DiffBuilder implements Builder<List<Diff>> {
private final List<Diff> diffs = new ArrayList<Diff>();
public List<Diff> build() {
return Collections.unmodifiableList(new ArrayList<Diff>(diffs));
}
public DiffBuilder append(final String fieldName, final boolean lhs, final
boolean rhs) {
if ( /* different */ ) {
diffs.add(new Diff<Boolean>(fieldName) {
public Boolean getLeft() {
return Boolean.valueOf(lhs);
}
public Boolean getRight() {
return Boolean.valueOf(rhs);
}
});
}
}
}
{code}
The above example would avoid _storing_ your primitives as Objects, for
whatever small additional storage costs that would have incurred.
$0.02,
Matt
> There should be a DifferenceBuilder with a ReflectionDifferenceBuilder
> implementation
> -------------------------------------------------------------------------------------
>
> Key: LANG-637
> URL: https://issues.apache.org/jira/browse/LANG-637
> Project: Commons Lang
> Issue Type: Improvement
> Components: lang.builder.*
> Reporter: Eric Lewis
> Priority: Minor
> Fix For: 3.x
>
> Attachments: DifferenceBuilder.java, DifferenceBuilderTest.java,
> Differentiable.java
>
>
> The ToStringBuilder and ReflectionToStringBuilder are great tools for
> everyday development.
> We use them to show all the properties in an object, which comes handy
> especially for testing.
> However, JUnit with its assertEquals() just outputs the toString() of the two
> compared objects. For complex objects, this becomes unreadable.
> So, it would be great to have a DifferenceBuilder with a
> ReflectionDifferenceBuilder implementation to be able to get only the
> differing properties of two objects. The question is whether the two objects
> would have to be of the same type or not.
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