I wish to make Vim open every file in read-only mode.
My use case is that I use Vim as both my editor and a gdb frontend via the Pyclewn plugin. I typically have one instance of Vim open for editing and another for debugging. I wish that the debugging instance would always open source files in read-only mode so that I do not get the ".swp file already exists" prompt, or that I accidentally edit a file without meaning to.