Re: Multiple specification of constraints

"mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message news:40404af4$0$564$e4fe514c_at_news.xs4all.nl...
> This is to general. I look at it this way: There are more sets of
> constraints, each with a different purpose. The contraints at the
> database serve to protect the integrity of the managed set of data.
> The constraints at the user-interface on the other hand serve to assist
> the user in providing the data he needs to provide in order to achieve
> his goal.

By this definition, those aren't constraints. A customer service rep also assists users - are they constraints? (oops, I guess sometimes they are)

Constraints are those things that must hold true. When possible, the GUI shouldn't allow users to do otherwise. However, the operations the user performs on the GUI can result in intermediate states which are NOT valid according to constraints - for example, they're just not done entering all the data yet. So it may be an issue of temporal granularity - the GUI has to guide the user toward properly-constrained data. But I'd hesitate to call those constraints, even if they are implied by constraints.

• Eric