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node: make builtin libs available for --eval
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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: #6207
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
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addaleax authored and Myles Borins committed Apr 20, 2016
1 parent 83bc0a2 commit 457f24f
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Showing 5 changed files with 48 additions and 23 deletions.
3 changes: 2 additions & 1 deletion doc/api/cli.markdown
Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,8 @@ The output of this option is less detailed than this document.

### `-e`, `--eval "script"`

Evaluate the following argument as JavaScript.
Evaluate the following argument as JavaScript. The modules which are
predefined in the REPL can also be used in `script`.


### `-p`, `--print "script"`
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3 changes: 3 additions & 0 deletions lib/internal/bootstrap_node.js
Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,9 @@
// 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
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35 changes: 34 additions & 1 deletion lib/internal/module.js
Original file line number Diff line number Diff line change
@@ -1,6 +1,10 @@
'use strict';

exports = module.exports = { makeRequireFunction, stripBOM };
exports = module.exports = {
makeRequireFunction,
stripBOM,
addBuiltinLibsToObject
};

exports.requireDepth = 0;

Expand Down Expand Up @@ -44,3 +48,32 @@ 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
});
});
}
23 changes: 2 additions & 21 deletions lib/repl.js
Original file line number Diff line number Diff line change
Expand Up @@ -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, const, function, ' +
Expand Down Expand Up @@ -559,23 +556,7 @@ REPLServer.prototype.createContext = function() {
this.lines = [];
this.lines.level = [];

// make built-in modules available directly
// (loaded lazily)
exports._builtinLibs.forEach(function(name) {
Object.defineProperty(context, name, {
get: function() {
var lib = require(name);
context._ = context[name] = lib;
return lib;
},
// allow the creation of other globals with this name
set: function(val) {
delete context[name];
context[name] = val;
},
configurable: true
});
});
internalModule.addBuiltinLibsToObject(context);

return context;
};
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7 changes: 7 additions & 0 deletions test/parallel/test-cli-eval.js
Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,13 @@ child.exec(nodejs + ' --eval "require(\'' + filename + '\')"',
assert.equal(status.code, 42);
});

// Check that builtin modules are pre-defined.
child.exec(nodejs + ' --print "os.platform()"',
function(status, stdout, stderr) {
assert.strictEqual(stderr, '');
assert.strictEqual(stdout.trim(), require('os').platform());
});

// module path resolve bug, regression test
child.exec(nodejs + ' --eval "require(\'./test/parallel/test-cli-eval.js\')"',
function(status, stdout, stderr) {
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