Initial add

* implemented conversion to simple units

README.org

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+* units-global-mode
+
+This mode uses [[https://www.gnu.org/software/units/units.html][gnu units]] to facilitate unit conversions inside emacs.
+
+*This package is a work in progress*
+
+* Features
+- [X] convert region to other units
+- [ ] check ~--conformable~ units
+
+
+* Example
+
+If you have
+
+    L = 23 ft
+
+And you ran ~units-convert-region-and-insert~ while selecting ~23 ft~ you'll be asked for target unit and with ~mm~ you get:
+
+    L = 23 ft = 7010.4 mm
+
+Similarly,
+
+    g = 9.81 m/s^2
+    g = 9.81 m/s^2 = 32.185039 ft/s^2
+
+There is completion for the target unit, that is non-exhaustive as it only includes defined units and not derived ones like ~ft/s^2~
+
+Running ~units-convert-region~ will just show the converted results in the minibuffer.
+
+If there is errors, like units aren't matched then it'll end with the error from ~units~

tests/units-tests.el

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+;; Run all tests using (ert t)
+
+;; conversion tests
+(ert-deftest units-convert-single-test ()
+  (should (= (units-convert-single 10 "ft" "m") 3.048))
+  (should (= (units-convert-single 1 "m" "ft") 3.2808399))
+  (should (= (units-convert-single 1 "kg" "g") 1e3))
+  (should (= (units-convert-single 1 "hour" "seconds") (* 60 60)))
+  (should (= (units-convert-single 1 "day" "hour") 24)))
+
+(ert-deftest units-convert-test ()
+  (should (= (units-convert "10ft" "m") 3.048))
+  (should (= (units-convert "1 m" "ft") 3.2808399))
+  (should (= (units-convert "1kg" "g") 1e3))
+  (should (= (units-convert "1 hour" "seconds") (* 60 60)))
+  (should (= (units-convert "1 day" "hour") 24)))

units-mode.el

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+ ;;; units-mode.el --- conversion between different units -*- lexical-binding: t -*-
+
+;; Author: Gaurav Atreya <allmanpride@gmail.com>
+;; Maintainer:
+;; Version: 0.1
+;; Package-Requires: ((emacs "28.1"))
+;; Homepage: https://github.com/Atreyagaurav/units-mode
+;; Keywords: units,conversion,global-mode
+
+
+;; This file is not part of GNU Emacs
+
+;; This program is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+
+;;; Commentary:
+
+;; This is emacs interface to gnu units program <https://www.gnu.org/software/units/units.html>.
+
+;;; Code:
+
+(defcustom units-binary-path "units"
+  "Path to the units binary.")
+
+(defcustom units-default-args "-t"
+  "Default args to add to units command.")
+
+(defcustom units-user-args ""
+  "Extra args for user to add to units command.")
+
+(defun units-command (value to-unit)
+  (shell-command-to-string
+   (format "%s %s %s \"%s\" \"%s\""
+	   units-binary-path
+	   units-default-args
+	   units-user-args
+	   value to-unit)))
+
+
+(defun units-command-conformable (value)
+  (shell-command-to-string
+   (format "%s %s --conformable \"%s\""
+	   units-binary-path
+	   units-default-args
+	   value)))
+
+(defun units-convert (value to-unit)
+  (let ((out-lines (split-string (string-trim-right (units-command value to-unit)) "\n")))
+    (if (length= out-lines 1)
+	(string-to-number (car out-lines))
+      (user-error "%s" (string-join out-lines "\n")))))
+
+(defun units-convert-single (value from-unit to-unit)
+  (units-convert (format "%s %s" value from-unit) to-unit))
+
+
+(defun units-conformable-list (value)
+  (split-string
+   (string-trim
+    (units-command-conformable value)) "\n"))
+
+(defun units-convert-region (region-text to-unit)
+  (interactive
+   (let ((region-text
+	  (buffer-substring-no-properties
+	   (region-beginning) (region-end))))
+      (list region-text
+	    (completing-read
+	     "Convert to: "
+	     (units-conformable-list region-text)))))
+  (message "%s" (units-convert region-text to-unit)))
+
+(defun units-convert-region-and-insert (region-text to-unit)
+  (interactive
+   (let ((region-text
+	  (buffer-substring-no-properties
+	   (region-beginning) (region-end))))
+      (list region-text
+	    (completing-read
+	     "Convert to: "
+	     (units-conformable-list region-text)))))
+  (save-excursion
+    (goto-char (region-end))
+    (insert (concat " = "
+		    (number-to-string
+		     (units-convert region-text to-unit))
+		    " "
+		    to-unit))))
+
+(provide 'units-mode)
+
+;;; units-mode.el ends here