If you set things up correctly, you can even get most IDEs to automatically fill in method signatures by making guesses based on what's currently in scope. This can save a lot of typing when it works, and even when it doesn't, it doesn't usually waste any keystrokes.
Absolutely, but can it complete column names in your database table? Or Redis commands? Or long hard-to-spell English words and sentences? :)
Vim will autocomplete based on whatever you have in the buffers. So when writing sql I sometimes open up a new buffer and paste the output of desc table.
