`io::Cursor` is a bit out of place

[alexcrichton]

I think this may not wish to use io::Cursor pervasively. This use case doesn't have much to do with std::io. The std version also stores a u64 which isn't needed for bytes's use case I believe.

[alexcrichton]

I also just twitch a bit whenever I see io::Cursor, I sort of regret adding it to std, it doesn't seem to really pull its weight.

[carllerche]

Makes sense. I mostly opted for Cursor to not add another type.

Another option would be to bring back ByteBuf or something like that?

[alexcrichton]

I think a local "cursor type" (w/e the name) may be right here, but I wouldn't add it just yet (I don't know what it should look like)

[est31]

I also just twitch a bit whenever I see io::Cursor, I sort of regret adding it to std, it doesn't seem to really pull its weight.

A bit off topic, but note that I love it being in std, you can easily use it to Read over a buffer. Very interesting when you only offer a io::Read based API and people want to use it with their memory buffered data (best use case is tests).

[carllerche]

Using Cursor here is definitely a mistake on my part...

std implements Read and Write for &[u8] and &mut [u8] respectively. We probably want to follow that pattern and implement Buf / BufMut for &[u8] and &mut [u8].

[tarcieri]

+1 on this. io::Cursor complicates no_std usage. I had to vendor it in to my PR to add no_std support: #135

Perhaps I should change that PR to just stop using io::Cursor entirely?

[tarcieri]

I opened a PR which vendors std::io::Cursor as buf::Cursor (while also reducing the position counter size to u32): #146

I'm not sure that's entirely ideal but I don't see any other path forward here. I need something like it to make progress on #135

[seanmonstar]

So to clarify what will happen in v0.5:

• impl Buf for Bytes directly (remove IntoBuf of Cursor<Self>)
• impl Buf for BytesMut directly (remove IntoBuf of Cursor<Self>)
• impl IntoBuf for &Bytes to return &[u8]
• impl IntoBuf for &BytesMut to return &[u8]
• impl IntoIterator for Bytes to use slice::Iter
• impl IntoIterator for BytesMut to use vec::IntoIter

Look right?

[carllerche]

Looks bout right.

[YetAnotherMinion]

I am looking at implementing IntoBuf for BytesMut, to solve the tokio-io problem. I am trying to understand what needs to happen

Am I reading the issues correctly that you want to get rid of Cursor. Does the replacement implementation you have in mind look like adding a position field to Bytes and BytesMut structs?