Hello, Sean.
2012/8/7 Sean Bartell <wingedtachik...@gmail.com>:
>> First, if you specify an unknown field in a switch (run with hex:00)
>> transform main = struct {
>> switch (.non_existent) {
>> 1: { };
>> else: { };
>> }
>> };
>> Bithenge would enter some endless recursion and eventually die.
>
> The problem is that in order to find ".non_existent", Bithenge tries to
> figure out whether the "switch" generates ".non_existent", which means
Do I understand it right that the switch could be driven by a value
assigned inside that switch? That would hardly make sense.
> it has to find ".non_existent". I've added this to the future feature
> list, even though it's more of a bug than a feature.
I would consider the endless loop definitely a bug. Especially if an
error in the script results in a page fault.
>> Do you think you can improve that somehow? Either by defining more
>> fine-grained error codes or returning bigger context or ...?
>
> I think the solution would be to put some sort of error information in
> the bithenge_scope_t. I've also added this to the future feature list.
That would be very nice. I think that just adding a char * member to
which you could assign more descriptive messages would be enough.
>> Last thing - do you think it would be possible to support recursive
>> structures? At least a simple variant that a structure can reference
>> itself? I am not sure that it is possible at all with current design
>> but it might be a natural way of describing some data...
>> What I have in mind is this:
>> transform recursive = struct {
>> .have_next <- nonzero_boolean <- uint8;
>> .data <- whatever;
>> if (.have_next) {
>> .next <- recursive;
>> }
>> }
>
> Well, this case could be handled with do...while:
Yes. As a matter of fact, my example was a simplified workaround for
not having the possibility to use fields as inputs to another
transform.
> Other cases would still need recursion, and it wouldn't be too hard to
> implement, so I've added it to the future feature list.
I agree. But it is definitely not a high-priority issue.
Thanks.
- Vojta
>
> Thanks,
> Sean
>
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