Search for things with apropos

Until recently, I didn't even know that apropos was an actual word. I thought that it was just some gibberish that Emacs hackers invented to name a command. Turns out, it actually has a very appropriate meaning:

apropos

preposition

with reference to; concerning.

An apropos Hydra

I've just added this one to hydra-examples.el.

(defhydra hydra-apropos (:color blue
                         :hint nil)
  "
_a_propos        _c_ommand
_d_ocumentation  _l_ibrary
_v_ariable       _u_ser-option
^ ^          valu_e_"
  ("a" apropos)
  ("d" apropos-documentation)
  ("v" apropos-variable)
  ("c" apropos-command)
  ("l" apropos-library)
  ("u" apropos-user-option)
  ("e" apropos-value))

I recommend to bind it like this:

(global-set-key (kbd "C-c h") 'hydra-apropos/body)

Customary screenshot:

As you can see, there are a total of 7 apropos functions available. The most useful ones are apropos, apropos-command and apropos-variable. But apropos-value is very interesting as well: it will not match an object name with the input, but instead search for all objects whose contents match input. So, for instance, if you see something like "error 42" come up, and you don't know where it's coming from, it's likely that some variable holds the value 42. And that's when you use apropos-variable.

Apropos is like old-school googling, and I find it highly useful in finding the Emacs information that I need. I hope that you will find it useful as well. Happy hacking!