Re: [Visualpython-users] Backwards-compatibility problems in Visual 5

[Bruce S. <Bru...@nc...>]

In that case you should keep your own data structure with time sequence, 
because there's no guarantee that scene.objects will represent the 
objects in time-creation order.

Bruce Sherwood

Roberto Aguirre Maturana wrote:
>> After some discussion with David Scherer, we're convinced that
>> scene.objects should indeed remain a tuple in Visual 5.0, not a list. As
>> he says, "Lists are mutable, so the user can try to do things like del
>> scene.objects[2] and won't get any error message or indication that they
>> are not doing the right thing. IMO error checking is MORE important than
>> backward compatibility: hardly anyone will remember Visual 3 in a year,
>> but people will make the same errors forever."
> 
> I agree with most of the previous paragraph.
> 
> 
>> But I also have a question about the example code you show.
>>
>> m.pick is the object picked, so you already know the object. What value
>> is there in knowing the sequence position of this object in
>> scene.objects, where the order of the objects is not relevant?
>>
> 
> It is relevant, as long as the sequence itself is relevant.
> 
> Let's say that I'm taking GPS readings at regular intervals, marking a  
> route, then i draw those points in VPython, in the very same order they  
> where taken.
> 
> There are two ways I would like to access those points and getting any  
> associated info to them: either merely pointing-and-clicking, Or navigate  
> across the points sequence using keys defined as "Next" or "Previous". In  
> the last case, since those points belong to a route, it is desirable to  
> jump from point to point in the original order, either backwards or  
> forward.
> 
> Best regard,
> 
> Roberto.
>