[vorbis-dev] Yet another vf question...

[John Morton]

On Wednesday 17 December 2003 14:16, Michael Smith wrote:
>  On Tuesday 16 December 2003 18:48, John Morton wrote:
>  > Should I ov_clear a failed ov_open/test/test_open call?
>
>  No. I _think_ vorbisfile internally does this on failure, you shouldn't
> repeat it (but it should be harmless?).

A close look into the source shows that ov_clear is called inside _ov_open1 
and _ov_open2, so it's not necessary.

>  > The xmms plugin does an fclose on failure, and that seems to work, but I
>  > thought I ought to know for certain.
>
>  Shouldn't be neccesary, should be fairly harmless.
>
>  > (An observation: I think the quantity of questions and bugs raised along
>  > the lines of "I did open file, ov_open, ov_read, close file, open
>  > another file, ov_read, and it exploded", or "I tried to make vorbisfile
>  > go in [some language with a deceptively C like stdio] and it didn't
>  > work" are probably due to the asymmetry in the callback set - there are
>  > callback hooks for read, seek, tell and close, but none for open. Is
>  > there any particular reason for this? (I realize it's to late in the day
>  > to fix the API in any fashion, but it's possible that oggfile might be
>  > able to avoid this API usability flaw.))
>
>  There's no good reason for an open callback, really. I would argue that
> close doesn't really belong in vorbisfile either, Monty disagrees (and I
> don't feel strongly on that point). It's relatively difficult to do it
> sensibly, too - opening a generic
> byte-source-object-which-might-be-filelike-but-might-not can be fairly
> complex, fopen() like parameters would probably be
>  insufficient.

I think you're probably right. I think symetry in the callbacks would be a 
good thing so avoiding a close callback would be good. It's either that or a 
lot of documentation reminding people they need to do something a little 
conterintuitive.

I'll add writing a documentation patch to the list of things to do.

(the ov_read_float bug is in the tracker as 493, FYI).

John

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