Automatically rewrite elisp-style variable name to
camelCase/snake_case
reddit / emacs

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CommanderThunderous · 2022-03-03 19:10

Is there a package which automatically and intelligently rewrites
`variable-name` to `variableName` or `variable_name` depending on the
current major language mode? It should be intelligent enough to
account for cases where you're typing within the bounds of string
quotes. The more I think about this problem the more difficult I think
it would be to write such a package --- perhaps none exists.

As an example, let's suppose we're writing Python (with `|` as the
cursor):

Basic:

1. `variable-name|`
1. `variable-name |`
1. `variable_name |` (conversion performed)

In quotes:

1. `variable_name 'foo-bar|`
1. `variable_name 'foo-bar |`
1. `variable_name 'foo-bar |` (no conversion as the user is typing
within quotes)

In f-string:

1. `variable_name f'foo {bar-baz|`
1. `variable_name f'foo {bar-baz |`
1. `variable_name f'foo {bar_baz |` (conversion performed)

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crawsphi · 2022-03-03 19:35

I would never tell someone not to hack on their Emacs if they wanted
to, but, yes: https://github.com/zk-phi/electric-case

Also
https://www.emacswiki.org/emacs/CamelCase,
https://github.com/akicho8/string-inflection,
and the recently-introduced
https://gitlab.com/ideasman42/emacs-cycle-at-point

might have something for you.

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ieure · 2022-03-03 20:12

Don't know if there's a package, but I wrote this ages ago and still
use it fairly often:

https://gist.github.com/ieure/2d8fad2252a3aba406eb6700f758e49a

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nandryshak · 2022-03-03 22:13

https://github.com/akicho8/string-inflection

In order to discover this package, you could search for `case` on
melpa.org and sort by # of downloads.

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nnreddit-user · 2022-03-04 20:56

This makes an interesting use of the tree-sitter integration in
Commercial Emacs:

    src/emacs -Q \
      --eval "(custom-set-variables \
                (quote (font-lock-support-mode (quote tree-sitter-
lock-mode))))" \
      --eval "(defun camelot (beg _end old-len) \
                   (let ((prev (tree-sitter-node-at (max (point-min)
(1- beg)))) \
                    (cur (tree-sitter-node-at beg))) \
                     (when (and (zerop old-len) \
                           (equal \"identifier\" (tree-sitter-node-
type prev)) \
                           (not (equal \"identifier\" (tree-sitter-
node-type cur)))) \
                       (let* ((start (tree-sitter-node-start prev)) \
                         (end (tree-sitter-node-end prev)) \
                         (identifier (buffer-substring-no-properties
start end)) \
                         (rep (replace-regexp-in-string
\"_\\\\(\\\\w\\\\)\" \
                               (lambda (m) (upcase (match-string 1
m))) \
                               identifier))) \
                    (unless (equal rep identifier) \
                      (save-excursion \
                        (goto-char start) \
                        (delete-char (- end start)) \
                        (insert rep)))))))" \
      --eval "(c-mode)" \
      --eval "(add-hook (quote after-change-functions) (function
camelot) t t))" \
      --eval "(dolist (c (split-string \"camel_this_now \" \"\")) \
                   (insert c) (redisplay) (sleep-for 0 200))" \
      --eval "(insert \"(\")" \
      --eval "(dolist (c (split-string \"\\\"dont_camel_me_bro \\\"\"
\"\")) \
                   (insert c) (redisplay) (sleep-for 0 200))" \
      --eval "(insert \")\n\")"