Recently I am indulging in Emacs. I tried to use it as my LaTeX tool, so I installed pdf-tools. If I add
in my init file, it will take about 2 seconds to start Emacs. So I want to write a function such that "pdf-tools-install" will run after I open a pdf file. But "add-hook" only works when a major mode is recognized, and we can recognize pdf only after pdf-tools is installed. I think it may relate to regex, but I don't know much about it. Could you help me with this function? Thanks!