Module handler_drop

handler_drop

An example of handling cleanup logic by implementing Drop for the handler. The plugin attaches to the current buffer, then sets the first 2 lines, which get sent back to us with a nvim_buf_lines_event notification. We handle this notification by saving the lines in the handler. We then let nvim close the channel, and wait for the IO loop to finish. The handler gets dropped, and so our cleanup logic is executed.

Usage

First, build the neovim included as a submodule:

cd neovim
make

See https://github.com/neovim/neovim/wiki/Building-Neovim for build options. Nothing is really needed to run the example.

After that, run the example via

cargo run --example handler_drop

You can verify it worked by looking at the file handler_drop.txt in the project directory which should contain 2 lines (“xyz” and “abc”).

Description

• The associated type for our Handler is the stdin of our child. But tokio’s ChildStdin does not implement futures::io::AsyncWrite, so it needs to be wrapped in the provided Compat type.

• Implementing Drop is straightforward, except that we cannot do so asynchronously. Since dropping the handler is one of the last things our plugin does, it’s not problem to run even larger code bodies synchronously here.

• The event handling code is not efficient, because we just read the arguments by reference and clone them. It’s easy to take ownership directly by matching on the enum Value directly, though.

• There’s basically no error handling, other than unwraping all the Results.

• awaiting the io future handle is probably not necessary, but feels like a nice thing to do.

• As with the other examples, we implement Spawn for our NeovimHandler most trivially.