Re: comments on Matrix

On Fri, Mar 22, 2013 at 9:51 AM, Benoit Jacob <jacob.benoit.1@gmail.com>wrote:

>
>
> 2013/3/22 Rik Cabanier <cabanier@gmail.com>
>
>>
>>
>> On Fri, Mar 22, 2013 at 1:48 AM, Robert O'Callahan <robert@ocallahan.org>wrote:
>>
>>> On Fri, Mar 22, 2013 at 7:48 AM, Rik Cabanier <cabanier@gmail.com>wrote:
>>>
>>>>  On Thu, Mar 21, 2013 at 11:38 AM, Tab Atkins Jr. <jackalmage@gmail.com
>>>> > wrote:
>>>>
>>>>> Only if you actually throw it.  It's not eagerly created every call.
>>>>>
>>>>
>>>> I worked a little with the mozilla code base and it seems that they
>>>> always create the object.
>>>> It's probably not a huge amount of overhead since it's not dynamically
>>>> allocated.
>>>>
>>>
>>> We certainly don't create a JS exception object if an exception is not
>>> actually thrown.
>>>
>>
>> If a function is marked as throwing in the IDL, doesn't it get an
>> exception object as a parameter on the C++ side?
>>
>
> No, in Mozilla's case it gets a so-called ErrorResult object,
>
>
> http://dxr.mozilla.org/mozilla-central/dom/bindings/ErrorResult.h?from=ErrorResult#l34
>
> C++ can then decide to call its Throw() method to actually produce an
> exception.


Yes, that's the one I was thinking of.