Using Emacs - 30 - elfeed part 2 - Hydras

# COMMENTS

In part 1, I talked about elfeed, a really awesome feed reader for emacs. Generally, I'm really liking it but there's been one problem - not being able to navigate quickly between groups of feeds with a keystroke or two.

It's emacs so there has to be a solution.

Enter hydra - a terrific emacs package from the same guy who brought us swiper, another one of my favorite emacs packages.

Basically, Hydra allows us to create Hydras - a collection of emacs commands tied o a single prefix along with a nice interface and help system.

Truth be told, I don't use hydra as much anymore since which-key does such a great job most of the time. Which-key, however, is no help here.

Here's the code to install hydra along with a some of sample Hydra's I use:

(use-package hydra
:ensure t)

;; Hydra for modes that toggle on and off
(global-set-key
(kbd "C-x t")
(defhydra toggle (:color blue)
"toggle"
("a" abbrev-mode "abbrev")
("s" flyspell-mode "flyspell")
("d" toggle-debug-on-error "debug")
("c" fci-mode "fCi")
("f" auto-fill-mode "fill")
("t" toggle-truncate-lines "truncate")
("w" whitespace-mode "whitespace")
("q" nil "cancel")))

;; Hydra for navigation
(global-set-key
(kbd "C-x j")
(defhydra gotoline
( :pre (linum-mode 1)
:post (linum-mode -1))
"goto"
("t" (lambda () (interactive)(move-to-window-line-top-bottom 0)) "top")
("b" (lambda () (interactive)(move-to-window-line-top-bottom -1)) "bottom")
("m" (lambda () (interactive)(move-to-window-line-top-bottom)) "middle")
("e" (lambda () (interactive)(end-of-buffer)) "end")
("c" recenter-top-bottom "recenter")
("n" next-line "down")
("p" (lambda () (interactive) (forward-line -1))  "up")
("g" goto-line "goto-line")
))

;; Hydra for some org-mode stuff
(global-set-key
(kbd "C-c t")
(defhydra hydra-global-org (:color blue)
"Org"
("t" org-timer-start "Start Timer")
("s" org-timer-stop "Stop Timer")
("r" org-timer-set-timer "Set Timer") ; This one requires you be in an orgmode doc, as it sets the timer for the header
("p" org-timer "Print Timer") ; output timer value to buffer
("w" (org-clock-in '(4)) "Clock-In") ; used with (org-clock-persistence-insinuate) (setq org-clock-persist t)
("o" org-clock-out "Clock-Out") ; you might also want (setq org-log-note-clock-out t)
("j" org-clock-goto "Clock Goto") ; global visit the clocked task
("c" org-capture "Capture") ; Don't forget to define the captures you want http://orgmode.org/manual/Capture.html
("l" (or )rg-capture-goto-last-stored "Last Capture"))

Take a look at the Hydra home page for detailed information.

With Hydra installed, I can creat one for navigating in elfeed:

`(defhydra mz/hydra-elfeed ()
"filter"
("c" (elfeed-search-set-filter "@6-months-ago +cs") "cs")
("e" (elfeed-search-set-filter "@6-months-ago +emacs") "emacs")
("d" (elfeed-search-set-filter "@6-months-ago +education") "education")
("*" (elfeed-search-set-filter "@6-months-ago +star") "Starred")
("M" elfeed-toggle-star "Mark")
("A" (elfeed-search-set-filter "@6-months-ago") "All")
("T" (elfeed-search-set-filter "@1-day-ago") "Today")
("Q" bjm/elfeed-save-db-and-bury "Quit Elfeed" :color blue)
("q" nil "quit" :color blue)
)

and add a binding to the elfeed key map: