julienfantin / KnR

RIP Denis Ritchie

The C programming language, aka K&R

Just working through the book’s exercices, using emacs and org-mode’s literate programming package org-babel.

Org-babel prerequisites

Redefined org-babel-C-execute

In order to feed raw text to the blocks STDIN while they are executed, a new header argument :cat is defined.

Its purpose is to provide a relative path to a text file, whose contents will be piped into the src block’s executable when at runtime.

(defun org-babel-C-execute (body params)
  "This function should only be called by `org-babel-execute:C'
or `org-babel-execute:C++'."
  (let* ((tmp-src-file (org-babel-temp-file
                        "C-src-"
                        (cond
                         ((equal org-babel-c-variant 'c) ".c")
                         ((equal org-babel-c-variant 'cpp) ".cpp"))))
         (tmp-bin-file (org-babel-temp-file "C-bin-"))
         ;; +
         (cat (cdr (assoc :cat params)))
         (cmdline (cdr (assoc :cmdline params)))
         (flags (cdr (assoc :flags params)))
         (full-body (org-babel-C-expand body params))
         (compile
          (progn
            (with-temp-file tmp-src-file (insert full-body))
            (org-babel-eval
             (format "%s -o %s %s %s"
                     (cond
                      ((equal org-babel-c-variant 'c) org-babel-C-compiler)
                      ((equal org-babel-c-variant 'cpp) org-babel-C++-compiler))
                     (org-babel-process-file-name tmp-bin-file)
                     (mapconcat 'identity
                                (if (listp flags) flags (list flags)) " ")
                     (org-babel-process-file-name tmp-src-file)) ""))))
    ((lambda (results)
       (org-babel-reassemble-table
        (if (member "vector" (cdr (assoc :result-params params)))
            (let ((tmp-file (org-babel-temp-file "c-")))
              (with-temp-file tmp-file (insert results))
              (org-babel-import-elisp-from-file tmp-file))
          (org-babel-read results))
        (org-babel-pick-name
         (cdr (assoc :colname-names params)) (cdr (assoc :colnames params)))
        (org-babel-pick-name
         (cdr (assoc :rowname-names params)) (cdr (assoc :rownames params)))))
     (org-babel-trim
      ;; +
      (org-babel-eval (concat (if cat (concat "cat " cat " | " ) "")
                              tmp-bin-file
                              (if cmdline (concat " " cmdline) ""))
                      "")))))

(setq c-default-style "k&r"
      c-basic-offset 4)

(org-babel-do-load-languages
 'org-babel-load-languages
 '((emacs-lisp . t)
   (C . t)))

;; Convenience settings
;;
(setq org-confirm-babel-evaluate nil)
(define-key c-mode-map (kbd "C-c C-v") 'org-babel-detangle)

Review

Import notes from the pdf

K.W.L.

What I knew

• Control Flow
• Syntax

What I wanted to know

• Pointers
• Data Structures
• I/O

What I learned