Vim auto commands: writing a read-only file?

Question

I'm using Perforce with Vim on Windows. I currently have an auto command set up to open a read-only file for edit when changing it:

au FileChangedRO * !p4 edit <afile>

Is there any way to set up a similar auto command to execute p4 edit when attempting to write a read-only file rather than edit it?

Answer 1

You can use an auto command attached to the BufWritePre event, that checks whether the file is read only or not and executes p4 edit on demand. Something like:

autocmd BufWritePre * :if &readonly | !p4 edit %