Change the name of ArrayBoundsException in druntime

[Denis Koroskin]

On Wed, 22 Oct 2008 19:06:24 +0400, Andrei Alexandrescu  
<SeeWebsiteForEmail at erdani.org> wrote:

> Jarrett Billingsley wrote:
>> On Wed, Oct 22, 2008 at 6:49 AM, Jacob Carlborg <doobnet at gmail.com>  
>> wrote:
>>> I think the name ArrayBoundsException should be changed to a more  
>>> general
>>> name like BoundsException, OutOfBoundsException or
>>> IndexOutOfBoundsException. Then you can use the exception in every  
>>> class
>>> that have some sort of index operation and not just for an array/array
>>> class.
>>>
>>  2nded.
>
> I agree. In fact I wanted to ask you all the following question. What do
> you think about the current exception hierarchy in phobos? I think it is
> terrible. Each module in std you open, the first piece of code to be
> seen is the "class ThisModuleNameException" definition. In many (most?)
> cases the module-specific exception does absolutely nothing in addition
> to its base class. The putative reader (including me) tends to scroll  
> non-critically over that passage without even blinking, mumbling in a  
> trance - of course, yes, each module should define at least one  
> exception type.
>
> Until one day when you stop scrolling and say, wait a minute. This all  
> is repetition. And there are alternatives to catching by type - you can  
> catch the base type and consult a field. And in fact I don't remember  
> seeing code that depends on exceptions thrown from different modules  
> having different types. There's something wrong here!
>
> I think most exception classes in phobos should be yanked if it's  
> possible for their functionality (often nil) to be moved in the  
> Exception base class. The module name should be a member. If someone  
> needs to deal with an exception thrown from a specific module, they can  
> always inspect the field. We don't need a huge hierarchy for that.
>
>
> Andrei

There is sometimes a need to differentiate between a specific exception  
and a generic one, even though the former or does nothing.

typedef Exception MyException; // might be a good compromise

try {
     throw new MyException("reason");
} catch (MyException e) {
     // catch concrete exception
} catch (Exception e) {
     // catch generic exception
}

This code currently doesn't work, because compiler thinks that MyException  
and Exception are of the same type, which is wrong - MyException is kind  
of a subclass of Exception, as the following sample shows:

typedef Exception MyException;

void main()
{
     MyException me = new MyException("reason");
     Exception e = me; // implicit downcast
     me = e; // doesn't work, it is an upcast
     Object o = me; // ICE! :)
}

Could anyone put it into bugzilla? (I have no access to HTTP currently :()