Question: Why don't fugitive buffers have acwrite 'buftype'?

[tmillr]

Usually you can easily detect whether a buffer will use autoccmds for writing just by checking its 'buftype'; this doesn't seem to work with fugitive however, as it doesn't set 'buftype' to acwrite for its BufWriteCmd buffers. Why not?

[tpope]

All buftype=acwrite does is tell Vim that the buffer name is "unrelated to a file". That is, it's identical to buftype=nofile, except it doesn't block :write from working. This means, for example, that the buffer name won't be written to a session file, because if it's not related to a file, then you wouldn't be able to :edit it. But you can edit fugitive:// file names. As far as Vim is concerned, they are related to a (virtual) file.

An alternative you might find helpful (depending on your use case) is to look for buffer names that look like URLs. Try @% =~# '^\a\+:[\/][\/]' (the backslashes are necessary to match on Windows).

[tmillr]

Thank you! I learned something new. I wish more authors were this friendly and helpful, and cared this much about their users. Definitely worth a donation.