File: C:/Ruby27-x64/share/doc/ruby/html/NilClass.html
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<h3>Parent</h3>
<p class="link"><a href="Object.html">Object</a>
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<h3>Methods</h3>
<ul class="link-list" role="directory">
<li ><a href="#method-i-26">#&</a>
<li ><a href="#method-i-3D-3D-3D">#===</a>
<li ><a href="#method-i-3D~">#=~</a>
<li ><a href="#method-i-5E">#^</a>
<li ><a href="#method-i-inspect">#inspect</a>
<li ><a href="#method-i-nil-3F">#nil?</a>
<li ><a href="#method-i-rationalize">#rationalize</a>
<li ><a href="#method-i-to_a">#to_a</a>
<li ><a href="#method-i-to_c">#to_c</a>
<li ><a href="#method-i-to_d">#to_d</a>
<li ><a href="#method-i-to_f">#to_f</a>
<li ><a href="#method-i-to_h">#to_h</a>
<li ><a href="#method-i-to_i">#to_i</a>
<li ><a href="#method-i-to_r">#to_r</a>
<li ><a href="#method-i-to_s">#to_s</a>
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<main role="main" aria-labelledby="class-NilClass">
<h1 id="class-NilClass" class="class">
class NilClass
</h1>
<section class="description">
<p>The class of the singleton object <code>nil</code>.</p>
</section>
<section id="5Buntitled-5D" class="documentation-section">
<section id="public-instance-5Buntitled-5D-method-details" class="method-section">
<header>
<h3>Public Instance Methods</h3>
</header>
<div id="method-i-26" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
false & obj → false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
nil & obj → false
</span>
</div>
<div class="method-description">
<p>And—Returns <code>false</code>. <em>obj</em> is always evaluated as it is the argument to a method call—there is no short-circuit evaluation in this case.</p>
<div class="method-source-code" id="26-source">
<pre>static VALUE
false_and(VALUE obj, VALUE obj2)
{
return Qfalse;
}</pre>
</div>
</div>
</div>
<div id="method-i-3D-3D-3D" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
obj === other → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Case Equality – For class <a href="Object.html"><code>Object</code></a>, effectively the same as calling <code>#==</code>, but typically overridden by descendants to provide meaningful semantics in <code>case</code> statements.</p>
<div class="method-source-code" id="3D-3D-3D-source">
<pre>VALUE
rb_equal(VALUE obj1, VALUE obj2)
{
VALUE result;
if (obj1 == obj2) return Qtrue;
result = rb_equal_opt(obj1, obj2);
if (result == Qundef) {
result = rb_funcall(obj1, id_eq, 1, obj2);
}
if (RTEST(result)) return Qtrue;
return Qfalse;
}</pre>
</div>
</div>
</div>
<div id="method-i-3D~" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
nil =~ other → nil
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Dummy pattern matching – always returns nil.</p>
<div class="method-source-code" id="3D~-source">
<pre>static VALUE
nil_match(VALUE obj1, VALUE obj2)
{
return Qnil;
}</pre>
</div>
</div>
</div>
<div id="method-i-5E" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
false ^ obj → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
nil ^ obj → true or false
</span>
</div>
<div class="method-description">
<p>Exclusive Or—If <em>obj</em> is <code>nil</code> or <code>false</code>, returns <code>false</code>; otherwise, returns <code>true</code>.</p>
<div class="method-source-code" id="5E-source">
<pre>static VALUE
false_xor(VALUE obj, VALUE obj2)
{
return RTEST(obj2)?Qtrue:Qfalse;
}</pre>
</div>
</div>
</div>
<div id="method-i-inspect" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
inspect → "nil"
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Always returns the string “nil”.</p>
<div class="method-source-code" id="inspect-source">
<pre>static VALUE
nil_inspect(VALUE obj)
{
return rb_usascii_str_new2("nil");
}</pre>
</div>
</div>
</div>
<div id="method-i-nil-3F" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
nil? → true
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Only the object <em>nil</em> responds <code>true</code> to <code>nil?</code>.</p>
<div class="method-source-code" id="nil-3F-source">
<pre>static VALUE
rb_true(VALUE obj)
{
return Qtrue;
}</pre>
</div>
</div>
</div>
<div id="method-i-rationalize" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
rationalize([eps]) → (0/1)
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns zero as a rational. The optional argument <code>eps</code> is always ignored.</p>
<div class="method-source-code" id="rationalize-source">
<pre>static VALUE
nilclass_rationalize(int argc, VALUE *argv, VALUE self)
{
rb_check_arity(argc, 0, 1);
return nilclass_to_r(self);
}</pre>
</div>
</div>
</div>
<div id="method-i-to_a" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_a → []
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Always returns an empty array.</p>
<pre class="ruby"><span class="ruby-keyword">nil</span>.<span class="ruby-identifier">to_a</span> <span class="ruby-comment">#=> []</span>
</pre>
<div class="method-source-code" id="to_a-source">
<pre>static VALUE
nil_to_a(VALUE obj)
{
return rb_ary_new2(0);
}</pre>
</div>
</div>
</div>
<div id="method-i-to_c" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_c → (0+0i)
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns zero as a complex.</p>
<div class="method-source-code" id="to_c-source">
<pre>static VALUE
nilclass_to_c(VALUE self)
{
return rb_complex_new1(INT2FIX(0));
}</pre>
</div>
</div>
</div>
<div id="method-i-to_d" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_d → bigdecimal
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns nil represented as a <a href="BigDecimal.html"><code>BigDecimal</code></a>.</p>
<pre class="ruby"><span class="ruby-identifier">require</span> <span class="ruby-string">'bigdecimal'</span>
<span class="ruby-identifier">require</span> <span class="ruby-string">'bigdecimal/util'</span>
<span class="ruby-keyword">nil</span>.<span class="ruby-identifier">to_d</span> <span class="ruby-comment"># => 0.0</span>
</pre>
<div class="method-source-code" id="to_d-source">
<pre><span class="ruby-comment"># File ext/bigdecimal/lib/bigdecimal/util.rb, line 145</span>
<span class="ruby-keyword">def</span> <span class="ruby-identifier ruby-title">to_d</span>
<span class="ruby-constant">BigDecimal</span>(<span class="ruby-value">0</span>)
<span class="ruby-keyword">end</span></pre>
</div>
</div>
</div>
<div id="method-i-to_f" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_f → 0.0
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Always returns zero.</p>
<pre class="ruby"><span class="ruby-keyword">nil</span>.<span class="ruby-identifier">to_f</span> <span class="ruby-comment">#=> 0.0</span>
</pre>
<div class="method-source-code" id="to_f-source">
<pre>static VALUE
nil_to_f(VALUE obj)
{
return DBL2NUM(0.0);
}</pre>
</div>
</div>
</div>
<div id="method-i-to_h" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_h → {}
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Always returns an empty hash.</p>
<pre class="ruby"><span class="ruby-keyword">nil</span>.<span class="ruby-identifier">to_h</span> <span class="ruby-comment">#=> {}</span>
</pre>
<div class="method-source-code" id="to_h-source">
<pre>static VALUE
nil_to_h(VALUE obj)
{
return rb_hash_new();
}</pre>
</div>
</div>
</div>
<div id="method-i-to_i" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_i → 0
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Always returns zero.</p>
<pre class="ruby"><span class="ruby-keyword">nil</span>.<span class="ruby-identifier">to_i</span> <span class="ruby-comment">#=> 0</span>
</pre>
<div class="method-source-code" id="to_i-source">
<pre>static VALUE
nil_to_i(VALUE obj)
{
return INT2FIX(0);
}</pre>
</div>
</div>
</div>
<div id="method-i-to_r" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_r → (0/1)
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Returns zero as a rational.</p>
<div class="method-source-code" id="to_r-source">
<pre>static VALUE
nilclass_to_r(VALUE self)
{
return rb_rational_new1(INT2FIX(0));
}</pre>
</div>
</div>
</div>
<div id="method-i-to_s" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
to_s → ""
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-description">
<p>Always returns the empty string.</p>
<div class="method-source-code" id="to_s-source">
<pre>static VALUE
nil_to_s(VALUE obj)
{
return rb_cNilClass_to_s;
}</pre>
</div>
</div>
</div>
<div id="method-i-7C" class="method-detail ">
<div class="method-heading">
<span class="method-callseq">
false | obj → true or false
</span>
<span class="method-click-advice">click to toggle source</span>
</div>
<div class="method-heading">
<span class="method-callseq">
nil | obj → true or false
</span>
</div>
<div class="method-description">
<p>Or—Returns <code>false</code> if <em>obj</em> is <code>nil</code> or <code>false</code>; <code>true</code> otherwise.</p>
<div class="method-source-code" id="7C-source">
<pre>static VALUE
false_or(VALUE obj, VALUE obj2)
{
return RTEST(obj2)?Qtrue:Qfalse;
}</pre>
</div>
</div>
</div>
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