Re: [wxhaskell-devel] wxHaskell repo restored to code.haskell.org

[<E....@br...>]

On Fri, Jun 03, 2011 at 12:14:58 +0100, Jeremy O'Donoghue wrote:
>    - Bugfix for assert error in SearchDynamicEventTable which was found in
>    debug builds. I believe that this is a proper fix for an issue Eric noted a
>    couple of months back.

It's not just debug builds (of what?), but basically the scenario where
you naively type "cabal install wx" on MacOS after having installed the
Haskell Platform and nothing else.   Macs ship with wxWidgets, albeit
with this crucial bit of missing functionality.

I'm a bit concerned that this may result in silently-does-the-wrong-thing
errors

+  if (evtHandler->GetDynamicEventTable() != NULL)
+    found = evtHandler->SearchDynamicEventTable( event );

As I'd discovered to my dismay, without this trawl through the non-existent
dynamic event table, things like scrolled list boxes stop responding to events.
  http://www.mail-archive.com/wxh...@li.../msg00580.html

If I understand the patch correctly, the result of this is that (A)
users would be able to happily install wxHaskell on Mac without any
prerequisites, but (B) if they were to use such a widget, it would just
silently not-work.

Much better to blow up from the beginning, I'm afraid :-(

Perhaps what we need is to use this opportunity to give a more friendly
error, something like this pseudocode
 
else {
  friendlyError $ "Your wxWidgets is missing a feature needed by wxHaskell."
               ++ "See http://haskell.org/haskell/wxHaskell for instructions"
               ++ "on installing a complete wxWidgets on your computer"
}

The even better solution would be for somebody to go understand how the event
handling code works and propose a solution that works without the missing
dynamic event table

-- 
Eric Kow <http://erickow.com>