Snippets
Execute command in shell buffer
comint-send-string is the function we’re looking for.1 shell is built on top of the comint library.
It takes a PROCESS and a STRING. You can get the process from the
shell buffer, and conveniently the shell function returns the buffer, so
you can streamline it all into something like:
(defun my-server ()
"SSH to my.server.com in `shell' buffer."
(interactive)
(comint-send-string
(get-buffer-process (shell))
"ssh my.server.com\n"))Where the (shell) call will take care of creating the shell buffer and/or process if necessary.2 n.b. if there’s an existing one, shell will re-use that.
Free variables
In some situations, for instance when setting a variable in a DOOM Emacs like
(setq my/variable "value")You might get the warning
Warning: assignment to free variable `er/try-expand-list'This is because set and setq do not declare lexical variables3 Only let does. .
The solution is to use4 But not quote the symbol.
(defvar my/variable "value")Lists to arrays
List of lists
To convert a list of lists, e.g.
(defvar mylist (("1" "a") ("2" "b") ("3" "c")))The method to convert a single element from the list is
(require 'cl)
(coerce (nth 0 mylist) 'vector)
;; ["1" "a"]We now just need to map this for all the list
(mapcar (lambda (arg) (coerce arg 'vector)) mylist) Lists conversion
To convert a vector to list:
(coerce [1 2 3] 'list)
;; (1 2 3)and to convert a list to vector:
(coerce '(1 2 3) 'vector)
;; [1 2 3]Reference
defcustom
You can specify variables using defcustom so that you and others can
then use Emacs’s customize feature to set their values. (You cannot
use customize to write function definitions; but you can write
defuns in your .emacs file. Indeed, you can write any Lisp
expression in your .emacs~ file.)5 The docs for defcustom:
https://www.gnu.org/software/emacs/manual/html_node/eintr/defcustom.html ## Footnotes
SQLite
Emacs provides functionality to interact with SQLite databases. For
these examples we will use the
emacSQL package. To open a database
file /tmp/foo.sqlite we issue:
(defvar db (emacsql-sqlite "~/tmp/foo.sqlite"))We can then issue SELECT statements with
;; Query the database for results:
(emacsql db [:select [name id]
:from people
:where (> salary 62000)])
;; => (("Susan" 1001))