buffer: introduce Buffer.encode() method

doc/api/buffer.markdown

@@ -290,6 +290,25 @@ Example: build a single Buffer from a list of three Buffers:
     // <Buffer 00 00 00 00 ...>
     // 42
 
+### Class Method: Buffer.encode(str[, encoding])
+
+* `str` {String} string to encode.
+* `encoding` {String} encoding to use, Optional.
+* Return: Buffer
+
+Encoding a string with more safely.
+
+  const str = '100';
+  const number = 100;
+  const buf1 = new Buffer(str); // allocate 3 bytes
+  const buf2 = new Buffer(number); // allocate 100 bytes
+
+  const value = ? // when value is come from outside
+
+  const buf3 = new Buffer(value); // wtf?
+
+  const buf4 = Buffer.encode(value); // allocate bytes safely
+
 ### Class Method: Buffer.isBuffer(obj)
 
 * `obj` Object

lib/buffer.js

@@ -195,6 +195,13 @@ Buffer.compare = function compare(a, b) {
   return binding.compare(a, b);
 };
 
+Buffer.encode = function(str, encoding) {
+  // convert string safely
+  if (typeof str !== 'string') {
+    str = '' + str;
+  }
+  return new Buffer(str, encoding);
+};
 
 Buffer.isEncoding = function(encoding) {
   var loweredCase = false;