On 8/30/22 15:37, Nicolas George wrote:
Leo Izen (12022-08-30):
Is there a reason this is AVWriter wr = foo() and not AVWriter *wr = foo()?
Most other APIs return pointers to structs, rather than structs themselves
(see: av_packet_alloc). Using a pointer would prevent us from having
sizeof(AVWriter) as part of the ABI, as was done with AVPacket.
Yes: to return a pointer, you need somewhere to store the structure. One
of the point of AVWriter is that you can store it on the stack to avoid
dynamic allocations when the string is short enough.
Note that AVWriter is exactly two pointers. It will always be two
pointers, and all the objects that I intend to introduce later will
always be two pointers: one const pointer for the methods, one pointer
for the object itself.
This design is essential to the features I promised for AVWriter and for
later.
I don't see how you are planning on avoiding dynamic allocations by
stack-allocating AVWriter when AVWriter itself only contains two pointers.
I also don't see how this design is essential to the features you
promised in a way that can't be done by just not making sizeof(AVWriter)
part of the ABI and returning pointers to a struct.
- Leo Izen (thebombzen)
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