[Laszlo-user] API Change Proposal: SetVisibility to replace SetVisible

[William Powell]

I agree with Geoff's suggestion. Changing the
behaviour of setVisible would impact a lot of programs
as well. Do it Geoff's way.
Bill Powell
--- Geoff Crawford <geoff at innov8cs.com> wrote:

> At 03:48 PM 9/28/2007, P T Withington wrote:
> >Please comment on this proposed API change which we
> would like to
> >implement for 4.1 (RingDing).
> >
> >Problem:
> >
> >SetVisible currently accepts null|false|true, where
> null has the
> >special meaning 'let data control visibility'. 
> This is a poor
> >interface because it is too easy to accidentally
> pass a value of
> >null.  The `visible` attribute cannot be used to
> ask programmatically
> >if a view is visible or not for the data-bound
> case.
> >
> >Proposal:
> >
> >1. Add a new attribute `visibility` that is a
> read/write String and
> >has values  'visible', 'hidden', 'collapse'. This
> is implemented by a
> >setter that  maps 'visible' -> true, 'hidden' ->
> false, 'collapse' ->
> >null in the old  mechanism.
> >
> >2. Deprecate `setVisible`:  issue a warning telling
> how to get the
> >same effect with `setVisibility`.  Make `visible`
> reflect the actual
> >state of the view (do not store the value passed to
> `setVisible`).
> >
> >3. In the next major release make `setVisible` a
> no-op so that
> >`visible` is read-only and reflects the actual
> state of the view
> >(i.e., if `visibility` is 'collapse', it will be
> true when there is
> >data and false otherwise).
> >
> >Evaluation:
> >
> >Pro:  1) Replaces an error-prone interface.  2)
> Solves the problem of
> >programmatically query a view's visible state.  3)
> Uses an interface
> >that is compatible with CSS.
> >
> >Con:  1) Programs will have to be updated to use
> the new API.
> 
> I understand the need, that's valid.  But breaking
> old code
> this way is not desirable - I've got an ERP system
> we're building
> that would be dramatically affected.
> 
> Suggestion: Make the new attribute and method as
> described.
> And also make the method work as stated, basically
> it
> adjusts the old visible attribute as before. 
> However,
> don't make the old visible read-only - keep it and
> let the old behavior work as well.  It would only
> mean
> you'd have to add to the visible code something that
> also set "visibility" as well.  That would give
> two paths to essentially the same thing with neither
> one being broken by the new functionality.  Then
> stop publishing the old method in the documentation.
> Old code would work, but anyone new to the
> environment
> wouldn't be aware of the old methodology.
> 
> 
>
=======================================================================
> Geoff Crawford                       Phone:         
>   (973) 361 - 4224
> Innov8 Computer Solutions, LLC       FAX:           
>   (973) 537 - 6946
> 711 Route 10 East, Suite 204         Email:         
> geoff at innov8cs.com
> Randolph NJ 07869                    Web:
> http://www.processwareerp.com
> 
>                   ProcessWare ERP for the Chemical
> Industry
> 
> 
> 



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