Check the class of objects

[Chris Wright]

Mael wrote:
>> What's wrong with:
>>
>> if(isByteImage(u))
>> { do something; }
>> ...
>>
>> Either way, you still need the if-else block to determine what the image is 
>> at runtime.
> 
> Well, actually the point is that the action "do something" is consistent accross images except when trying to access data (compare bytes/floats/value/triples), and using a run time if inside the loops would be unefficient, that's why I want to only use static if in the loop, but still share most of the code since it's truly redundant 

Why not use the Visitor pattern?