From 26cb2aa9a1d5081662e8bc6e117697143508c349 Mon Sep 17 00:00:00 2001
From: oleg <oleg.korobenko@gmail.com>
Date: Thu, 4 Dec 2014 23:22:14 +0300
Subject: [PATCH] call callback once

---
 lib/command/spawn.js | 5 +++--
 lib/utils.js         | 9 +++++++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/lib/command/spawn.js b/lib/command/spawn.js
index a699d64..2e10c95 100644
--- a/lib/command/spawn.js
+++ b/lib/command/spawn.js
@@ -2,7 +2,8 @@
 
 var spawn = require('child_process').spawn,
 	ParentCommand = require('./base').Command,
-	inherits = require('util').inherits;
+	inherits = require('util').inherits,
+	utils = require('../utils');
 
 function Command(params) {
 	params = params || {};
@@ -22,6 +23,7 @@ Command.prototype.run = function(params, callback) {
 		stdout = '';
 	if (!params.cmd) return callback(new Error('`cmd` is not set'));
 	if (!params.args) return callback(new Error('`args` is not set'));
+	callback = utils.once(callback);
 	params.options = params.options || {};
 	params.options.cwd = params.options.cwd || this.cwd;
 	var cmd = spawn(params.cmd, params.args, params.options);
@@ -34,7 +36,6 @@ Command.prototype.run = function(params, callback) {
 		callback(new Error('Spawned command outputs to stderr: ' + data));
 		cmd.kill();
 	});
-	// TODO; callback should be called only once (port once from underscore)
 	cmd.on('close', function(code) {
 		var err = null;
 		if (code !== 0) err = new Error(
diff --git a/lib/utils.js b/lib/utils.js
index 4c3fd27..53c72e0 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -13,3 +13,12 @@ exports.isObject = function(obj) {
 exports.noop = function() {};
 
 exports.slice = Array.prototype.slice;
+
+exports.once = function(func) {
+	var isCalled = false;
+	return function() {
+		if (isCalled) return;
+		func.apply(this, arguments);
+		isCalled = true;
+	};
+};