Close #1281 Make require a public member of module

Reviewed by @felixge

doc/api/modules.markdown

@@ -172,6 +172,17 @@ y.js:
     console.log(x.a);
 
 
+### module.require
+
+The `module.require` method provides a way to load a module as if
+`require()` was called from the original module.
+
+Note that in order to do this, you must get a reference to the `module`
+object.  Since `require()` returns the `exports`, and the `module` is
+typically *only* available within a specific module's code, it must be
+explicitly exported in order to be used.
+
+
 ### All Together...
 
 To get the exact filename that will be loaded when `require()` is called, use

lib/module.js

@@ -336,6 +336,11 @@ Module.prototype.load = function(filename) {
 };
 
 
+Module.prototype.require = function(path) {
+  return Module._load(path, this);
+};
+
+
 // Returns exception if any
 Module.prototype._compile = function(content, filename) {
   var self = this;
@@ -343,7 +348,7 @@ Module.prototype._compile = function(content, filename) {
   content = content.replace(/^\#\!.*/, '');
 
   function require(path) {
-    return Module._load(path, self);
+    return self.require(path);
   }
 
   require.resolve = function(request) {

test/fixtures/module-require/child/index.js

@@ -0,0 +1,2 @@
+exports.loaded = require('target');
+exports.module = module;

test/fixtures/module-require/child/node_modules/target.js

@@ -0,0 +1 @@
+exports.loaded = 'from child';

test/fixtures/module-require/parent/index.js

@@ -0,0 +1,5 @@
+var child = require('../child');
+//console.log(child.module.require, child.module);
+console.log(child.module.require('target'));
+console.log(child.loaded);
+exports.loaded = child.module.require('target');

test/fixtures/module-require/parent/node_modules/target.js

@@ -0,0 +1 @@
+exports.loaded = 'from parent';

test/simple/test-module-loading.js

@@ -207,6 +207,13 @@ var amdExtraArgs = require(amdFolder + '/extra-args.js');
 assert.equal(amdExtraArgs.ok, amdreg.ok, 'amd extra args failed');
 
 
+// make sure that module.require() is the same as
+// doing require() inside of that module.
+var parent = require('../fixtures/module-require/parent/');
+var child = require('../fixtures/module-require/child/');
+assert.equal(child.loaded, parent.loaded);
+
+
 process.addListener('exit', function() {
   assert.ok(common.indirectInstanceOf(a.A, Function));
   assert.equal('A done', a.A());