[Seaside] Bread crumbs

[Colin Putney]

> This approach works well for navigating static data structures (like 
> the
> Yahoo hierarchy Julian mentioned, or a Wiki), but doesn't make much 
> sense
> for workflow.  Work flow has much more interesting problems.  One way
> you can think about modelling it is that you want to be able to create
> links which, when clicked on, act as if the user had backtracked to a
> particular earlier page and hit reload - so the breadcrumb trail is a 
> more
> controlled form of back button.

 From a UI point of view I think this would be a really nice feature in 
many applications. The key is to use bread crumbs selectively, with 
regard to the logic of the application. If it's just a straight 
backtracking through the pages the user has viewed, it doesn't give the 
user anything more than the History menu in the browser. But if you 
only leave bread crumbs for "significant" pages, where significant is 
defined in terms of the application's problem domain and workflow 
structure, it could be really handy.

> One way to implement this would be for the session to hand out 
> "bookmark"
> objects, which, when sent #value, would simulate the user backtracking 
> to
> the point at which they were captured. You could capture these 
> bookmarks
> at every step, and build up a trail of links which would activate the
> appropiate bookmark when clicked on, and the user would be whisked 
> back to
> the right page exactly as if they had clicked the back button to get
> there.

I like it.

> This is potentially even more confusing to developers than the use of 
> the
> back button - these "bookmark" objects are essentially raw 
> continuations -
> but maybe if I don't point that out they won't be scary...

Doesn't sound like a problem to me. It's probably not something you 
want to introduce right at the beginning of a tutorial, but anyone who 
knows they need something like this won't be scared off. To put it 
another way, anyone who understands Seaside's flow control well enough 
to use #call: and #answer: won't have any problem with this. If they 
don't understand call/answer, they won't be using bookmarks anyway.

Colin