Re: [Planner Dev] patch to add support for FF and SF relationships

[Kurt Maute <kurt maute us>]

On Mon, 2006-04-03 at 21:33 +0200, Alvaro del Castillo wrote:
> Hi Kurt!

Hi Alvaro!  Good to hear from you!  Hope you are well.

> Add task t1 
> Add task t2
> Change t2 duration to 5d.
> Add predecessor for t2 with t1 (Edit task->Predecessors) using FF.
> 
> Task t2 will start 4 days before the start of the project which
> shouldn't be possible.
> 
> SF: Start to finish
> 
> If I add a new task "t1" to a new project and create a second task "t2"
> and the make t2 depends on t1 as SF t2 the starts before the project
> start date and playing with zoom in and zoom out you can lost the "t2"
> task in the canvas gantt view.
> 
> So I think a new test to be sure the relation doesn't create a task
> starting before the start of the project should be added.

Good catch.  That's not something I thought of. We can disallow SF if
(predecessor start = project start) easily enough.  However, I don't
know that I can or want to hunt down every possible way that someone can
make a task start before the project start date.

For instance, if I check when the FF or SF relationship is created, then
I can stop it, but if the initial check is ok, the user might at some
point extend the estimated work and push it back beyond the start date
(or change resource allocations).

The only other solution I can think of is to do a final check in
calculate_task_start_from_finish and set start =
MAX(start,project_start).  I actually just tried this out.  The result
is the task is scheduled as if the SF/FF relationship were not there.

Which do you think is worse?  Scheduling prior to start or invalidating
the relationship?  Maybe there's another solution I haven't thought of?

-- 
Kurt Maute <kurt maute us>