Java has Comparable and Comparator to compare objects. Object has an
equals() method. But what are we meant to do when and object has
multiple ways of being equal?
Consider an database row that has a name, code and a value. Equality
could be based on
* database id
* code
* name and code
* case-insensitive name
Any of these could be appropriate in different situations - in the same
way we use Comparators, we should be able to use Equators.
When extended to collections, this allows us to search for specific
values (with an EqualsPredicate that takes an Equator), and implement
Maps and Sets that use specific equators to determine uniqueness (a
HashEquator interface may also be defined for this).
However, it is also useful for general coding and equality checking.
Does this mean it's suitable for Lang (not really knowing anything about
that project)? Is there a Predicate class in Lang?
If an Equator is determined to be something worthwhile for the next
(generic) version of Collections, I can provide interfaces, default
implementations tests etc.
Cheers
Stephen Kestle
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