何必东奔西走 Emacs应有尽有

之前还写了一个bc-mode 但今天突然发现Emacs的calc就可以进行我需要的计算 也提供了一个快捷函数quick-calc 我还是觉得不方便 所以可以把给bc-mode写的函数改一下

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(defun run-calc (expr &optional replace)
  "Calculate the `expr' using GNU bc.
If called interactively, the user is asked for input.  If called on
region the selected expression is used as input.  By default display
output in temp buffer `*BC Output*'.  With prefix, insert the output."
  (interactive
   (list (if (use-region-p)
	     (buffer-substring-no-properties
	      (region-beginning)
	      (region-end))
	   (quick-calc current-prefix-arg))
	 current-prefix-arg))
  (require 'calc)
  (let ((output (calc-eval expr)))
    (if (and replace output)
	(when (use-region-p)
	  (delete-region (region-beginning) (region-end))
	  (insert output))
      (message "Result: %s" output))))

和bc相比缺点有：

  • 运算速度慢
  • bc支持简单的编程而这个只能用elisp了