How do I open a file and manipulate it in VimScript without displaying it in a window?

Question

Is there a way I can open a file in VimL/VimScript and keep it hidden from the user? I am writing a plugin which is attempting to figure out exactly what it should do by looking for and potentially searching the content of certain files. Currently I am doing an :sview to open the file in a new window. After using :global/.../y a to search the file and read out the results of what I found, I :close the file. However, by this way of doing it there is a chance for a strange user experience of seeing a file you did not explicitly request to be opened flash open momentarily before you and then close again. My current approach does what I need, but I would like to find a less visually jarring way to do this.

How do I open a file in VimScript in a way that I can manipulate it (read-only) without showing it in a window?

Answer 1

Another answer that allows you to use a buffer.

Vim is single threaded, and any vimscript you run will run completely without the GUI being refreshed in the middle. So the new window flashing before the user is not a problem - you'll be done with it before Vim has a chance to refresh the screen.

What the user can notice, is the layout change. sview opens the buffer in a new window, so Vim might resize the currently open windows. When you close the temporary window the other windows will be resized again - the the end result might not be the same as the original sizes.

The solution? don't create a new window. Load the temporary buffer to the current window with :view, do whatever you need to do with it, return to the original buffer with :buffer, and close the temporary buffer with :bdelete(unless you want to keep it loaded.

This, ofcourse, will pose a problem if the currently loaded buffer is changed. :hide to the rescue! :hide {cmd} will run {cmd} as if the current buffer is set to hidden. That means that any command that switches the window to another buffer will simply hide the current buffer, even if it has changes.

So - simply load the temp buffer with :hide view. You might also want to restore it with :hide buffer, just in case something goes wrong and you introduce changes in the temp buffer(which means you should also close it with :bdelete!).