replace defcusom request-coding-system with key :coding-system

Not tested yet!

This code removes the new `request-coding-system` defcustom, and
instead uses a keyword parameter to the main `request` function. Since
this parameter needs to be passed down the chain several times I'm not
entirely certain that I've made the changes everywhere they need to be
made.

This commit also shifts the default form 'binary to 'utf-8.

README.rst

@@ -150,13 +150,13 @@ PUT JSON data including non-ascii strings:
 
 .. code:: emacs-lisp
 
-  (setq request-coding-system 'utf-8)
   (request
    "http://httpbin.org/put"
    :type "PUT"
    :data (json-encode '(("key" . "値1") ("key2" . "値2")))
    :headers '(("Content-Type" . "application/json"))
    :parser 'json-read
+   :coding-system 'utf-8
    :success (cl-function
              (lambda (&key data &allow-other-keys)
                (message "I sent: %S" (assoc-default 'json data)))))

request.el

@@ -64,10 +64,6 @@
   "Directory to store data related to request.el."
   :type 'directory)
 
-(defcustom request-coding-system 'binary
-  "coding-system for request."
-  :type 'symbol)
-
 (defcustom request-curl "curl"
   "Executable for curl command."
   :type 'string)
@@ -398,6 +394,7 @@ Example::
                        (files nil)
                        (parser nil)
                        (headers nil)
+                       (coding-system 'utf-8)
                        (success nil)
                        (error nil)
                        (complete nil)
@@ -413,18 +410,19 @@ Request.el has a single entry point.  It is `request'.
 ==================== ========================================================
 Keyword argument      Explanation
 ==================== ========================================================
-TYPE       (string)   type of request to make: POST/GET/PUT/DELETE
-PARAMS      (alist)   set \"?key=val\" part in URL
-DATA (string/alist)   data to be sent to the server
-FILES       (alist)   files to be sent to the server (see below)
-PARSER     (symbol)   a function that reads current buffer and return data
-HEADERS     (alist)   additional headers to send with the request
-SUCCESS  (function)   called on success
-ERROR    (function)   called on error
-COMPLETE (function)   called on both success and error
-TIMEOUT    (number)   timeout in second
-STATUS-CODE (alist)   map status code (int) to callback
-SYNC         (bool)   If `t', wait until request is done.  Default is `nil'.
+TYPE          (string)   type of request to make: POST/GET/PUT/DELETE
+PARAMS         (alist)   set \"?key=val\" part in URL
+DATA    (string/alist)   data to be sent to the server
+FILES          (alist)   files to be sent to the server (see below)
+PARSER        (symbol)   a function that reads current buffer and return data
+HEADERS        (alist)   additional headers to send with the request
+CODING-SYSTEM (symbol)   coding system for tempfiles ('utf by default)
+SUCCESS     (function)   called on success
+ERROR       (function)   called on error
+COMPLETE    (function)   called on both success and error
+TIMEOUT       (number)   timeout in second
+STATUS-CODE    (alist)   map status code (int) to callback
+SYNC            (bool)   If `t', wait until request is done.  Default is `nil'.
 ==================== ========================================================
 
 
@@ -574,6 +572,7 @@ and requests.request_ (Python).
                       (request--urlencode-alist params))))
   (setq settings (plist-put settings :url url))
   (setq settings (plist-put settings :response response))
+  (setq settings (plist-put settings :coding-system coding-system))
   (setf (request-response-settings response) settings)
   (setf (request-response-url      response) url)
   (setf (request-response--backend response) request-backend)
@@ -900,7 +899,7 @@ Currently it is used only for testing.")
     (make-directory (file-name-directory (request--curl-cookie-jar)) t)))
 
 (cl-defun request--curl-command
-    (url &key type data headers timeout response files* unix-socket
+    (url &key type data headers timeout response files* unix-socket coding-system
          &allow-other-keys
          &aux
          (cookie-jar (convert-standard-filename
@@ -927,10 +926,10 @@ Currently it is used only for testing.")
      (let ((tempfile (request--make-temp-file)))
        (push tempfile (request-response--tempfiles response))
        (let ((file-coding-system-alist nil)
-             (coding-system-for-write request-coding-system))
+             (coding-system-for-write coding-system))
          (with-temp-file tempfile
-           (setq buffer-file-coding-system request-coding-system)
-           (if (eq request-coding-system 'binary)
+           (setq buffer-file-coding-system coding-system)
+           (if (eq coding-system 'binary)
                (set-buffer-multibyte nil))
            (insert data)))
        (list "--data-binary" (concat  "@" (request-untrampify-filename tempfile)))))
@@ -1009,7 +1008,7 @@ temporary file paths."
         files))
 
 (cl-defun request--curl (url &rest settings
-                             &key type data files headers timeout response
+                             &key type data files headers timeout response coding-system
                              &allow-other-keys)
   "cURL-based request backend.
 
@@ -1046,12 +1045,12 @@ removed from the buffer before it is shown to the parser function.
                       (request--curl-normalize-files files)
                     (setf (request-response--tempfiles response) tempfiles)
                     (apply #'request--curl-command url :files* files*
-                           :response response settings)))
+                           :response response :coding-system coding-system settings)))
          (proc (apply #'start-file-process "request curl" buffer command)))
     (request-log 'debug "Run: %s" (mapconcat 'identity command " "))
     (setf (request-response--buffer response) buffer)
     (process-put proc :request-response response)
-    (set-process-coding-system proc request-coding-system request-coding-system)
+    (set-process-coding-system proc coding-system coding-system)
     (set-process-query-on-exit-flag proc nil)
     (set-process-sentinel proc #'request--curl-callback)))
 

tests/test-request.el

@@ -373,11 +373,11 @@ To check that, run test with:
 
 (request-deftest request-simple-post-multibyte-json ()
    :backends (curl)
-   (setq request-coding-system 'utf-8)
    (request-testing-with-response-slots
       (request-testing-sync "report/some-path"
                             :type "POST" :data "{\"鍵\": \"値\"}"
                             :headers '(("Content-Type" . "application/json"))
+                            :coding-system 'utf-8
                             :parser 'json-read)
     (should (equal status-code 200))
     (should (equal (assoc-default 'path data) "some-path"))