[jira] [Updated] (LANG-1708) Usage of "ReflectionDiffBuilder"

["Gilles Sadowski (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LANG-1708?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gilles Sadowski updated LANG-1708:
----------------------------------
    Attachment: LANG-1708.unit_test.patch

> Usage of "ReflectionDiffBuilder"
> --------------------------------
>
>                 Key: LANG-1708
>                 URL: https://issues.apache.org/jira/browse/LANG-1708
>             Project: Commons Lang
>          Issue Type: Wish
>          Components: lang.builder.*
>    Affects Versions: 3.13.0
>            Reporter: Gilles Sadowski
>            Priority: Major
>              Labels: functional, utility
>             Fix For: 3.14.0
>
>         Attachments: LANG-1708.unit_test.patch
>
>
> If we have either this class
> {code}
>     private static class MyDirect {
>         private float value;
>         MyDirect(float a) {
>             value = a;
>         }
>     }
> {code}
> or this class
> {code}
>     private static class MyReference {
>         private MyDirect value;
>         MyReference(float a) {
>             value = new MyDirect(a);
>         }
>     }
> {code}
> it could be argued that they are _functionally_ equivalent; IOW, code that uses one or the other (say, via a library) would consider it an implementation detail (e.g. if that library changed one for the other in some internal object).
> [{{ReflectionDiffBuilder}}|https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/builder/ReflectionDiffBuilder.html] however behaves differently: Two instances with the same information contents (a primitive {{float}} value, from the caller POV) are considered the same in the former case and *not the same* in the latter.
> It will be noted that neither class defines an {{equals(Object)}} method; were it the case, the documentation of {{ReflectionDiffBuilder}} [constructor|https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/builder/ReflectionDiffBuilder.html#ReflectionDiffBuilder-T-T-org.apache.commons.lang3.builder.ToStringStyle-] says:
> {noformat}
> If lhs == rhs or lhs.equals(rhs) then the builder will not evaluate any calls to append(...) and will return an empty DiffResult when build() is executed.
> {noformat}
> However there are the use-cases
> # (as above) where {{equals}} was not overridden (and the source code cannot be modified by the user who wants to list the differences, or ensure there are none, functionally), and
> # where one would want to list (potential) differences that could exist even if {{equals}} would return {{true}} (e.g. if {{equals}} is buggy).
> IMHO:
> * Current behaviour is inconsistent (even if intended).
> * There should be a way to disable the equality check (i.e. *always* use reflection to list the differences).



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