assert d["1"] is None, "Sanity prevails! 😌"
support. There is something of an inverse vertical integration penalty here:
，这一点在51吃瓜中也有详细论述
BYOB (bring your own buffer) reads were designed to let developers reuse memory buffers when reading from streams — an important optimization intended for high-throughput scenarios. The idea is sound: instead of allocating new buffers for each chunk, you provide your own buffer and the stream fills it.
Most userland implementations of custom ReadableStream instances do not typically bother with all the ceremony required to correctly implement both default and BYOB read support in a single stream – and for good reason. It's difficult to get right and most of the time consuming code is typically going to fallback on the default read path. The example below shows what a "correct" implementation would need to do. It's big, complex, and error prone, and not a level of complexity that the typical developer really wants to have to deal with: