-
Notifications
You must be signed in to change notification settings - Fork 0
/
index.html
285 lines (161 loc) · 8.33 KB
/
index.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
<!DOCTYPE html>
<!--[if IEMobile 7 ]><html class="no-js iem7"><![endif]-->
<!--[if lt IE 9]><html class="no-js lte-ie8"><![endif]-->
<!--[if (gt IE 8)|(gt IEMobile 7)|!(IEMobile)|!(IE)]><!--><html class="no-js" lang="en"><!--<![endif]-->
<head>
<meta charset="utf-8">
<title>Is variable an Object? - Plough => Ruby</title>
<meta name="author" content="andHapp">
<meta name="description" content="In Ruby, everything is an object. Well in Ruby 1.8, everything derives from an Object. However, in 1.9 a BasicObject has been introduced which is a...">
<!-- http://t.co/dKP3o1e -->
<meta name="HandheldFriendly" content="True">
<meta name="MobileOptimized" content="320">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="canonical" href="Plough => Ruby/2009/08/17/is-variable-an-object.html/">
<link href="/favicon.png" rel="icon">
<link href="/stylesheets/screen.css" media="screen, projection" rel="stylesheet" type="text/css">
<script src="/javascripts/modernizr-2.0.js"></script>
<script src="/javascripts/ender.js"></script>
<script src="/javascripts/octopress.js" type="text/javascript"></script>
<link href="/atom.xml" rel="alternate" title="Plough => Ruby" type="application/atom+xml">
<!--Fonts from Google"s Web font directory at http://google.com/webfonts -->
<link href="http://fonts.googleapis.com/css?family=PT+Serif:regular,italic,bold,bolditalic" rel="stylesheet" type="text/css">
<link href="http://fonts.googleapis.com/css?family=PT+Sans:regular,italic,bold,bolditalic" rel="stylesheet" type="text/css">
</head>
<body >
<header role="banner"><hgroup>
<h1><a href="/">Plough => Ruby</a></h1>
<h2>Journey through ruby</h2>
</hgroup>
</header>
<nav role="navigation"><ul class="subscription" data-subscription="rss">
<li><a href="/atom.xml" rel="subscribe-rss" title="subscribe via RSS">RSS</a></li>
</ul>
<form action="http://google.com/search" method="get">
<fieldset role="search">
<input type="hidden" name="q" value="site:Plough => Ruby" />
<input class="search" type="text" name="q" results="0" placeholder="Search"/>
</fieldset>
</form>
<ul class="main-navigation">
<li><a href="/">Blog</a></li>
<li><a href="/blog/archives">Archives</a></li>
</ul>
</nav>
<div id="main">
<div id="content">
<div>
<article class="hentry" role="article">
<header>
<h1 class="entry-title">Is Variable an Object?</h1>
<p class="meta">
<time datetime="2009-08-17T00:00:00+01:00" pubdate data-updated="true" >Aug 17<span>th</span>, 2009</time>
</p>
</header>
<div class="entry-content"><p>In Ruby, everything is an object. Well in Ruby 1.8, everything derives from an Object. However, in 1.9 a BasicObject has been introduced which is a minimalist version of a full blown object.</p>
<p>Right, so is variable an object in Ruby?</p>
<p>The answer is “no”. Let us look at the following code below and discuss what it does to reach a concrete solution. <br><br></p>
<pre>
person = "Tim"
</pre>
<br><br>
<p>This line basically creates a String object with the value “Tim” and stores it somewhere in the object heap. It then stores the reference of this object in the variable “person”. Thus, a variable is not an object. It is a mere pointer to an object. In other words, variables hold references to the objects and not the objects themselves.</p>
<p>This is similar to how sometimes CPU registers work. Instead of storing the next instruction, the registers store the memory address of the next instruction.</p>
<br><br>
<p><b>Update:</b></p>
<p>Continuing this discussion, I would like to add that variables when passed to methods are passed by <em>value</em>.</p>
<p>And? what does that mean?</p>
<p>Now, my contemporary Java and C developers (I like to call them geeks) would easily relate to the phrase “Pass by Value”. When a variable is passed by value then the variable is copied to another location and that new temporary variable that is created is passed to the method. Let us say the code for that is something like the snippet below:<br><br></p>
<pre>
x = "Tim"
y = x
</pre>
<br><br>
<p>Going back to the Ruby World. In Ruby, the variables are passed by value but since these values are actually the references to the object means the method can modify the underlying object. Let us prove this simple phenomenon. Take the code above and fire up the Terminal (or cmd line for Windows) and type irb to start a new irb session and do the following:<br><br></p>
<pre>
x="Tim";y=x;puts "Copied - #{y.object_id} and Original - #{x.object_id}"
</pre>
<p>and what do you see? Yeah that is correct they are the reference to the same object.</p>
</div>
<footer>
<p class="meta">
<span class="byline author vcard">Posted by <span class="fn">andHapp</span></span>
<time datetime="2009-08-17T00:00:00+01:00" pubdate data-updated="true" >Aug 17<span>th</span>, 2009</time>
</p>
<div class="sharing">
<a href="http://twitter.com/share" class="twitter-share-button" data-url="Plough => Ruby/2009/08/17/is-variable-an-object.html/" data-via="" data-counturl="Plough => Ruby/2009/08/17/is-variable-an-object.html/" >Tweet</a>
<div class="g-plusone" data-size="medium"></div>
<div class="fb-like" data-send="true" data-width="450" data-show-faces="false"></div>
</div>
<p class="meta">
<a class="basic-alignment left" href="/2009/08/16/hello-world.html/" title="Previous Post: Hello Ruby world!">« Hello Ruby world!</a>
<a class="basic-alignment right" href="/2009/08/18/method-arguments-in-ruby.html/" title="next Post: Method arguments in ruby">Method arguments in ruby »</a>
</p>
</footer>
</article>
</div>
<aside class="sidebar">
<section>
<h1>Recent Posts</h1>
<ul id="recent_posts">
<li class="post">
<a href="/2013/12/30/aspect-oriented-programming.html/">Aspect Oriented Programming</a>
</li>
<li class="post">
<a href="/2013/12/01/Mina-the-deployer.html/">Mina, the deployer</a>
</li>
<li class="post">
<a href="/2013/04/10/dtrace-probes-in-ruby-2.html/">DTrace probes in Ruby 2 and a startling discovery</a>
</li>
<li class="post">
<a href="/2013/04/08/openstruct-to-hash.html/">OpenStruct to hash</a>
</li>
<li class="post">
<a href="/2013/02/23/inspect-to_s-change-in-ruby2.html/">In Ruby2, inspect independent of to_s</a>
</li>
</ul>
</section>
</aside>
</div>
</div>
<footer role="contentinfo"><p>
Copyright © 2013 - andHapp -
<span class="credit">Powered by <a href="http://octopress.org">Octopress</a></span>
</p>
</footer>
<div id="fb-root"></div>
<script>(function(d, s, id) {
var js, fjs = d.getElementsByTagName(s)[0];
if (d.getElementById(id)) {return;}
js = d.createElement(s); js.id = id;
js.src = "//connect.facebook.net/en_US/all.js#appId=212934732101925&xfbml=1";
fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));</script>
<script type="text/javascript">
(function() {
var script = document.createElement('script'); script.type = 'text/javascript'; script.async = true;
script.src = 'https://apis.google.com/js/plusone.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(script, s);
})();
</script>
<script type="text/javascript">
(function(){
var twitterWidgets = document.createElement('script');
twitterWidgets.type = 'text/javascript';
twitterWidgets.async = true;
twitterWidgets.src = 'http://platform.twitter.com/widgets.js';
document.getElementsByTagName('head')[0].appendChild(twitterWidgets);
})();
</script>
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-7379349-5']);
_gaq.push(['_trackPageview']);
(function() {
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();
</script>
</body>
</html>