Should masked exceptions be an error?

[Nick Sabalausky]

"Brad Roberts" <braddr at bellevue.puremagic.com> wrote in message 
news:alpine.DEB.2.00.0911241319190.18188 at bellevue.puremagic.com...
> On Mon, 23 Nov 2009, Andrei Alexandrescu wrote:
>
>> Consider:
>>
>> try {
>>    ...
>> } catch (Exception) {
>>    ...
>> } catch (StdioException) {
>>    ...
>> }
>>
>> The second handler never matches because StdioException is a subclass of
>> Exception, so the first handler will always match whatever the second 
>> matches.
>>
>> Should that be a compile-time error? I think so.
>>
>>
>> Andrei
>
> Alternate thought.. should order matter or should it automatically sort
> such that most specific catch is preferred.  Sort of matches the
> declaration order doesn't (ok, shouldn't) matter philosophy.

Use first match:
+ Consistent with "else if"

Use most specific match:
+ Consistent with template pattern matching
+ Possibly more practical
- I can just imagine all the bugs this would probably have in DMD

Personally, I'm torn. I'd probably lean more towards "most specific match", 
but I'd be perfectly happy either way.