Updating Clojure namespaces

Continuing my experimentations with Emacs Lisp, I created a function that automatically updates the namespace of a Clojure buffer in conformity with its pathname. This is useful after renaming a file, since changing a file pathname requires to change its namespace, which is sometimes annoying to do by hand.

	(defun clojure-correct-ns
	()
	"Returns the namespace name that the file should have."
	(let* ((nsname ())
	(dirs (reverse (split-string (buffer-file-name) "/")))
	(aftersrc nil))
	(dolist (dir dirs)
	(when (not aftersrc)
	(if (or (string= dir "src") (string= dir "test"))
	(setq aftersrc t)
	(setq nsname (append nsname (list dir "."))))))
	(when nsname
	(replace-regexp-in-string "_" "-" (substring (apply 'concat (reverse nsname)) 1 -4)))))
	(defun clojure-update-ns
	()
	"Updates the namespace of the current buffer. Useful if a file has been renamed."
	(interactive)
	(let ((nsname (clojure-correct-ns)))
	(when nsname
	(clojure-find-ns) ;; function defined in clojure-mode
	(replace-match nsname nil nil nil 4))))

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Once added to your .emacs file, you can call it with:

M-x clojure-update-ns

It assumes clojure-mode is already loaded.

Earmuffs and variables

According to the Clojure coding standards for libraries, variables names should be written with *earmuffs* only when they are intended to be rebind.

Here and there I forget this rule and use earmuffs most of the time, so I decided to create an Emacs Lisp function to add/remove earmuffs to variable:

	(defun earmuffy (&optional arg)
	(interactive "P")
	(let* ((variable (thing-at-point 'sexp))
	(bounds (bounds-of-thing-at-point 'sexp))
	(current-point (point))
	(earmuffed-variable (concat "*" variable "*")))
	(save-excursion)
	(kill-region (car bounds) (cdr bounds))
	(if arg
	;; unearmuffy
	(progn
	(insert (substring variable 1 (- (length variable) 1)))
	(goto-char (- current-point 1)))
	;; earmuffy
	(progn
	(insert earmuffed-variable)
	(goto-char (+ current-point 1))))))

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Add it to your .emacs file and then place your cursor on a variable and call it with

M-x earmuffy

to add earmuffs, or type

C-u M-x earmuffy

to remove them.