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

[P T Withington]

It would be most helpful if you have comments on this proposal if you  
log them at:

http://jira.openlaszlo.org/jira/browse/LPP-4599

(I have already logged the comments so far).

On 2007-09-28, at 15:48 EDT, 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.
>
>
>