RE: Another take on versioning

> OK, so we need wording that says that if a pipeline contains a step  
> that it doesn't recognise (eg the v2 step in the above) then it must  
> not run any steps in the pipeline. Right? But that's a separate issue.

Right.

> 
> I thought you were going to give an illustration which showed:
> 
>    * one of the XProc 1.0 steps that has side effects (ie 
> p:store) has  
> an extra output port added to it in v2.0
> 
>    * that step is used in a v2.0 pipeline along with a step that is  
> sensitive to side-effects (eg p:directory-list)
> 
>    * the pipeline is set up such that the *only* dependency between  
> p:directory-list and p:store is through the extra output port
> 
> and persuade me to care that the person running the v2.0 
> pipeline with  
> a v1.0 processor didn't get the same output that they would have if  
> they'd have been running it in a v2.0 processor. Then I would have  
> argued that anyone designing a v2.0 pipeline that contains a  
> meaningful dependency based purely on a new output port, but 
> wants the  
> pipeline to be runnable in v1.0 processors, is going to have to do  
> some extra work introducing those dependencies through other means.  
> And that's OK.

This is actually a very nice example (which I haven't thought about at
all :), and I think I agree with your conclusions.

Regards,
Vojtech

Received on Monday, 12 October 2009 10:17:00 UTC