node: make builtin libs available for `--eval`

Make the builtin libraries available for the `--eval` and
`--print` CLI options, using the same mechanism that the
REPL uses.

This renders workarounds like `node -e 'require("fs").doStuff()'`
unnecessary.

As part of this, the list of builtin modules and the code for
adding the corresponding properties to the target context is moved
to `internal/module.js`, and the previously missing `repl` entry
is added.

PR-URL: https://github.com/nodejs/node/pull/6207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

3 files changed, 39 insertions, 22 deletions

diff --git a/lib/internal/bootstrap_node.js b/lib/internal/bootstrap_node.js
index 2960234fa0..195dfbc0fb 100644
--- a/lib/internal/bootstrap_node.js
+++ b/lib/internal/bootstrap_node.js
@@ -105,6 +105,9 @@
         // User passed '-e' or '--eval' arguments to Node without '-i' or
         // '--interactive'
         preloadModules();
+
+        const internalModule = NativeModule.require('internal/module');
+        internalModule.addBuiltinLibsToObject(global);
         evalScript('[eval]');
       } else if (process.argv[1]) {
         // make process.argv[1] into a full path
diff --git a/lib/internal/module.js b/lib/internal/module.js
index 9918c73626..aa1ffc0142 100644
--- a/lib/internal/module.js
+++ b/lib/internal/module.js
@@ -1,6 +1,10 @@
 'use strict';
 
-exports = module.exports = { makeRequireFunction, stripBOM };
+exports = module.exports = {
+  makeRequireFunction,
+  stripBOM,
+  addBuiltinLibsToObject
+};
 
 exports.requireDepth = 0;
 
@@ -46,3 +50,32 @@ function stripBOM(content) {
   }
   return content;
 }
+
+exports.builtinLibs = ['assert', 'buffer', 'child_process', 'cluster',
+  'crypto', 'dgram', 'dns', 'domain', 'events', 'fs', 'http', 'https', 'net',
+  'os', 'path', 'punycode', 'querystring', 'readline', 'repl', 'stream',
+  'string_decoder', 'tls', 'tty', 'url', 'util', 'v8', 'vm', 'zlib'];
+
+function addBuiltinLibsToObject(object) {
+  // Make built-in modules available directly (loaded lazily).
+  exports.builtinLibs.forEach((name) => {
+    Object.defineProperty(object, name, {
+      get: () => {
+        const lib = require(name);
+        // This implicitly invokes the setter, so that this getter is only
+        // invoked at most once and does not overwrite anything.
+        object[name] = lib;
+        return lib;
+      },
+      // Allow the creation of other globals with this name.
+      set: (val) => {
+        // Deleting the property before re-assigning it disables the
+        // getter/setter mechanism.
+        delete object[name];
+        object[name] = val;
+      },
+      configurable: true,
+      enumerable: false
+    });
+  });
+}
diff --git a/lib/repl.js b/lib/repl.js
index 82555497eb..d802ff304c 100644
--- a/lib/repl.js
+++ b/lib/repl.js
@@ -64,10 +64,7 @@ function hasOwnProperty(obj, prop) {
 // This is the default "writer" value if none is passed in the REPL options.
 exports.writer = util.inspect;
 
-exports._builtinLibs = ['assert', 'buffer', 'child_process', 'cluster',
-  'crypto', 'dgram', 'dns', 'domain', 'events', 'fs', 'http', 'https', 'net',
-  'os', 'path', 'punycode', 'querystring', 'readline', 'stream',
-  'string_decoder', 'tls', 'tty', 'url', 'util', 'v8', 'vm', 'zlib'];
+exports._builtinLibs = internalModule.builtinLibs;
 
 
 const BLOCK_SCOPED_ERROR = 'Block-scoped declarations (let, ' +
@@ -565,23 +562,7 @@ REPLServer.prototype.createContext = function() {
   this.lines = [];
   this.lines.level = [];
 
-  // make built-in modules available directly
-  // (loaded lazily)
-  exports._builtinLibs.forEach((name) => {
-    Object.defineProperty(context, name, {
-      get: () => {
-        var lib = require(name);
-        this.last = context[name] = lib;
-        return lib;
-      },
-      // allow the creation of other globals with this name
-      set: (val) => {
-        delete context[name];
-        context[name] = val;
-      },
-      configurable: true
-    });
-  });
+  internalModule.addBuiltinLibsToObject(context);
 
   Object.defineProperty(context, '_', {
     configurable: true,