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Posted to issues@commons.apache.org by "Thomas Neidhart (JIRA)" <ji...@apache.org> on 2012/07/15 13:21:34 UTC

[jira] [Updated] (COLLECTIONS-251) improving static factory methods for static importability, conistency

     [ https://issues.apache.org/jira/browse/COLLECTIONS-251?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Thomas Neidhart updated COLLECTIONS-251:
----------------------------------------

    Fix Version/s:     (was: 4.0-beta-1)
                   4.0
    
> improving static factory methods for static importability, conistency
> ---------------------------------------------------------------------
>
>                 Key: COLLECTIONS-251
>                 URL: https://issues.apache.org/jira/browse/COLLECTIONS-251
>             Project: Commons Collections
>          Issue Type: Improvement
>          Components: Bag, BidiMap, Buffer, Collection, Comparator, Core, Functor, Iterator, KeyValue, List, Map, Set
>    Affects Versions: 3.2
>            Reporter: Stephen Kestle
>             Fix For: 4.0
>
>
> Commons Collections uses the singleton "getInstance()" pattern and extends it to allow parameters etc to be passed in.  decorate() serves a similar purpose.
> I propose replacing both of these with getClassName() for the following reasons:
> 1. Static imports would mean that TruePredicate.getInstance() would be replaced with getTruePredicate().  getInstance() cannot be statically imported, because it is reduced to one class' getInstance(), where we are likely using many.
> 2. It gives subclasses a way to avoid compiler issues - COLLECTIONS-243 compile problems are generally because the compiler can't choose between Collection<T> and Set<T>.  Doing this change completely avoids this issue - even if there is a workaround, this makes life a lot easier (different compilers - eclipse - will allow things that the Sun one won't).  
> 2.1 Overridden and overloaded static methods are a really bad idea
> 2.2 No confusion about what class is being instantiated
> 2.3 As our methods become more useful in the generic sense, the compiler issues increase until you hit something that just won't work
> 3. Simple migration path - those using TruePredicate.getInstance() can switch to PredicateUtils.truePredicate() before updating to this version.
> 4. Allows a more consistent user environment.  Following the current pattern means that most people will have MyTransformer.getInstance(), while using TransformerUtils.nopTransformer().
> Our work will be made a lot easier if we make this change.

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