I wanted functionality like the SelectKey to switch to channels when I’m using the EmacsIRCClient. If I’m already in the channel, I just want the channel buffer to come up. If I’m not in the channel, but on the server, I want to just join the channel. If I’m not even on the server, I want to connect and then join the channel.

  (defun stesla-erc-join-channel (channel &optional invite)
    (when invite
        (erc-cmd-MSG (concat "ChanServ invite " channel))
        (with-temp-message "Waiting for ChanServ..." (sleep-for 5))))
    (erc-cmd-JOIN channel))

  (defun stesla-erc-join-or-switch-with-connect (server port nick full-name
                                                        channel &optional invite)
    "If we are not currently in CHANNEL on SERVER, join it.  If we are not
currently on SERVER:PORT as NICK, connect first.  Otherwise, just switch to the
    (let ((server-buffer (car (erc-buffer-list
                               (lambda () (and (string= server erc-session-server)
      (if server-buffer
          (let ((buffer (car (erc-buffer-list
                              (lambda () (and (string= channel (erc-default-target))
                                              (string= server erc-session-server)
            (if buffer
                (switch-to-buffer buffer)
                (set-buffer server-buffer)
                (stesla-erc-join-channel channel invite))))
          (erc-select :server server :port port :nick nick :full-name full-name)
          (with-temp-message "Waiting for NickServ..." (sleep-for 5))
          (stesla-erc-join-channel channel invite)))))

  ;; stesla-f5-prefix-map is a sparse keymap defined on [f5]
  (defvar stesla-erc-channel-map stesla-f5-prefix-map)

  (defun stesla-display-erc-channel-bindings ()
    (describe-bindings [f5]))

  (define-key stesla-erc-channel-map "?" 'stesla-display-erc-channel-bindings)

  (defmacro stesla-define-erc-key (fname-base key server port nick full-name channel &optional
    "Define an erc-key function FNAME-BASE bound on KEY that will execute
stesla-erc-join-or-switch-with-connect on the remaining params"
    (let ((fname (intern (concat "stesla-erc-channel-" (symbol-name fname-base))))
         (defun ,fname ()
            ,server ,port ,nick ,full-name ,channel ,invite))
         (define-key stesla-erc-channel-map ,key ',fname))))

  (put 'stesla-define-erc-key 'lisp-indent-function 2)