writef: split into writef() and writefv()

src/hulk/klog.d

@@ -40,9 +40,9 @@ struct Klog
      */
     public static void writef(string s, va_list args)
     {
-        hulk.writef.writef(s, args, function void(ubyte ch) {
+        hulk.writef.writefv(function void(ubyte ch) {
                     Console.write(ch);
-                });
+                }, s, args);
     }
 
     /**

src/hulk/serial.d

@@ -40,9 +40,9 @@ struct Serial
      */
     public static void writef(string s, va_list args)
     {
-        hulk.writef.writef(s, args, function void(ubyte ch) {
+        hulk.writef.writefv(function void(ubyte ch) {
                     Serial.write(ch);
-                });
+                }, s, args);
     }
 
     /**

src/hulk/writef.d

@@ -10,13 +10,13 @@ alias ch_out_fn = void function(ubyte);
 /**
  * Format a string and write characters to the given output function.
  *
+ * @param ch_out Character output function.
  * @param s Format string.
  * @param args Variable arguments structure.
- * @param ch_out Character output function.
  *
  * @return Number of characters written.
  */
-size_t writef(string s, va_list args, ch_out_fn ch_out)
+size_t writefv(ch_out_fn ch_out, string s, va_list args)
 {
     size_t length_written;
     bool escape = false;
@@ -90,6 +90,23 @@ size_t writef(string s, va_list args, ch_out_fn ch_out)
     return length_written;
 }
 
+/**
+ * Format a string and write characters to the given output function.
+ *
+ * @param ch_out Character output function.
+ * @param s Format string.
+ *
+ * @return Number of characters written.
+ */
+extern(C) size_t writef(ch_out_fn ch_out, string s, ...)
+{
+    va_list args;
+    va_start(args, s);
+    size_t rv = writefv(ch_out, s, args);
+    va_end(args);
+    return rv;
+}
+
 /**
  * Format a value in hexadecimal to the given output function.
  *