[osmosis-dev] API 0.6 and unique keys

[Brett Henderson]

marcus.wolschon at googlemail.com wrote:
> On Wed, 28 Jan 2009 23:02:28 +1100, Brett Henderson <brett at bretth.com>
> wrote:
>   
>> Have you tried the EntityBuilder classes?  They were intended to make 
>> this easier, or at least require less code.  The builder classes can be 
>> used in place of normal entity classes where you require a mutable 
>> object and only convert them to a true entity at the interface of your 
>> task.  It is something of an experiment though.  If they're never useful 
>> then I might scrap the idea.  I've used them in a number of places 
>> within the core osmosis tasks.  The database code uses them extensively 
>> because the code that reads basic entities is quite separate from the 
>> code that reads tags, way nodes, etc so it's useful to be able to build 
>> an entity up in stages.
>>     
>
> I did not know about them.
> I'll have a look. It sounds very usefull. :)
>   
This was my initial response to the whole "mutable" versus "immutable" 
entity discussion.  I was hoping that by creating builders to simplify 
entity manipulation that we could have it both ways, easy to modify 
entities, and guaranteed thread safety.  But I don't know if it was a 
good idea or not.  I think it's fairly neat, but is definitely more 
complex than just allowing entities to be modified directly.  It also 
incurs a performance penalty (although fairly small according to the 
performance stats I posted recently).  Feedback most welcome.

An example of their use is in the TagRemoverBuilder class.