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https://issues.apache.org/jira/browse/LANG-637?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Duncan Jones updated LANG-637:
------------------------------
Attachment: DifferenceBuilderTest.java
Differentiable.java
DifferenceBuilder.java
I've begun work on an implementation of this feature, attached are some partial
files. I would love some thoughts on whether the approach is sensible. Note
that a reflection based builder would be required, but is not yet sketched out.
I have defined a new interface, {{Differentiable<T>}}, that is similar to
{{Comparable<T>}}. The {{DifferenceBuilder}} will test user-chosen fields for
equality (much like {{EqualsBuilder}}) and will append any differing fields an
internal {{ToStringBuilder}} (one for each object). The {{build()}} method will
either return an empty string if the tested fields were equal, or a string of
the form:
{noformat}[LHS Object] differs from [RHS Object]{noformat}
(where the objects are printed using the {{ToStringBuilder}} and a user-chosen
style).
Expected usage is as follows (taken from JavaDoc):
{code}
public class Person implements Differentiable<Person> {
String name;
int age;
boolean smoker;
...
public String differentiateFrom(Person obj) {
// No need for null check, as NullPointerException correct if obj is null
return new DifferenceBuilder(this, obj, ToStringStyle.SHORT_PREFIX_STYLE)
.append("name", this.name, obj.name)
.append("age", this.age, obj.age)
.append("smoker", this.smoker, obj.smoker)
.build();
}
}
{code}
If the design appeals, I'll continue with the leg-work and add all the
necessary method overloads and additional constructors etc. I can then post an
update for a more detailed review.
> 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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