On 7/28/2010 2:14 PM, Chris Muller wrote:
> In Morph>>#handleMouseDown:, it sets the wasHandled: flag of the
> incoming Event to true.
>
> Isn't it more appropriate for wasHandled: to be set by the code that
> actually _handles_ the event?  i.e., in #mouseDown:?

It would be *very* error-prone if every mouseDown: handler had to mark 
the event explicitly as handled. The common case is that if you request 
to handle the event via #handlesMouseDown: then the assumption is that 
you will indeed handle it, and only if for some reason you decide that 
you need to reject it halfways through the handler you would explicit 
reset the handled flag.

> In my overridden mouseDown:, I have several code paths that may or may
> not choose to handle the event.  The logical approach seemed to be for
> each to simply checked #wasHandled and, if not, decide whether it
> wants to handle it and, if so, set wasHandled: true, so none of the
> subsequent possibilities will attempt to handle it.

You can still do that by initially resetting the wasHandled flag before 
going through your handler. However, do keep in mind that the flag isn't 
a "user flag" but rather that the flag will be used to determine if the 
event should instead be handled by one of your parent morphs. If that 
isn't the semantics you're trying to implement you should probably leave 
that flag alone.

Cheers,
   - Andreas