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http://issues.apache.org/jira/browse/COLLECTIONS-110?page=comments#action_12414304
 ] 

Sergei Ivanov commented on COLLECTIONS-110:
-------------------------------------------

Another problem we are going to face is that some of the current implementation 
decisions are not compatible with generics.
First of all, static singleton instances of e.g. various EmptyIterator's and 
trivial functors cannot be made generic. They can be wrapped in a static 
generified getInstance() method, which would still contain an unchecked cast.
Second, there are many "graceful fallback" cases, which become tricky with 
generics. Let's take TransformIterator as an example. Constructing it without a 
transformer is equivalent to constructing it with a NOPTransformer. However, 
NOPTransformer introduces a certain relation between expected input and output 
types: output type must be assignable from input type. There is no such 
relation (in fact, no relation at all) between generic parameter types for 
generic Transformer interface.

> [collections] Support parametized classes with commons.collections.
> -------------------------------------------------------------------
>
>          Key: COLLECTIONS-110
>          URL: http://issues.apache.org/jira/browse/COLLECTIONS-110
>      Project: Commons Collections
>         Type: Bug

>  Environment: Operating System: other
> Platform: Other
>     Reporter: Colbert Philippe

>
> It's time to create a parallel version of commons.collections to support 
> parametized classes of each container class and abstract class.  It's not 
> that 
> hard.  There is a 23 PDF document on Sun Java website describing in detail 
> how 
> it should be done and what to watch out for.
> I already converted a few classes from commons.collection privately for my 
> own 
> needs.  Once you get the hang of it, it's a rather quick process.
> I am even willing to volunteer my time to do some more but I need the 
> collaboration of some of the original programmers to watch over things.

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