Kernel.html

---
title: Kernel
layout: default
---
<div class="main">
    <div class="banner">
        
            <span>Ruby on Rails 8.0.0</span><br />
        
        <div class="type">Module</div>
        <h1>
            Kernel
            
        </h1>
        <ul class="files">
            
            <li><a href="../files/activesupport/lib/active_support/core_ext/kernel/concern_rb.html">activesupport/lib/active_support/core_ext/kernel/concern.rb</a></li>
            
            <li><a href="../files/activesupport/lib/active_support/core_ext/kernel/reporting_rb.html">activesupport/lib/active_support/core_ext/kernel/reporting.rb</a></li>
            
            <li><a href="../files/activesupport/lib/active_support/core_ext/kernel/singleton_class_rb.html">activesupport/lib/active_support/core_ext/kernel/singleton_class.rb</a></li>
            
        </ul>
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    <div id="bodyContent">
        <div id="content">
  

  

  
  


  

  
    <h2 id="methods">Methods</h2>
    <ul>
      
        <li>
          <a href="#method-i-class_eval">class_eval</a>
        </li>
      
        <li>
          <a href="#method-i-concern">concern</a>
        </li>
      
        <li>
          <a href="#method-i-enable_warnings">enable_warnings</a>
        </li>
      
        <li>
          <a href="#method-i-silence_warnings">silence_warnings</a>
        </li>
      
        <li>
          <a href="#method-i-suppress">suppress</a>
        </li>
      
        <li>
          <a href="#method-i-with_warnings">with_warnings</a>
        </li>
      
    </ul>
  

  

  
    

    

    

    

    <!-- Methods -->
    
    
      <h2 id="instance-public-methods">Instance Public methods</h2>
      
        <div class="method">
          <h3 id="method-i-class_eval">
            
              class_eval(*args, &amp;block)
            
          </h3>

          
            <div class="description">
              <p><a href="Kernel.html#method-i-class_eval"><code>class_eval</code></a> on an object acts like <code>singleton_class.class_eval</code>.</p>
            </div>
          

          

          

          
          
            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/kernel/singleton_class.rb, line 5
  def class_eval(*args, &amp;block)
    singleton_class.class_eval(*args, &amp;block)
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/kernel/singleton_class.rb#L5" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-concern">
            
              concern(topic, &amp;module_definition)
            
          </h3>

          
            <div class="description">
              <p>A shortcut to define a toplevel concern, not within a module.</p>

<p>See <a href="Module/Concerning.html"><code>Module::Concerning</code></a> for more.</p>
            </div>
          

          

          

          
          
            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/kernel/concern.rb, line 11
  def concern(topic, &amp;module_definition)
    Object.concern topic, &amp;module_definition
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/kernel/concern.rb#L11" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-enable_warnings">
            
              enable_warnings(&amp;block)
            
          </h3>

          
            <div class="description">
              <p>Sets $VERBOSE to <code>true</code> for the duration of the block and back to its original value afterwards.</p>
            </div>
          

          

          

          
          
            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 20
  def enable_warnings(&amp;block)
    with_warnings(true, &amp;block)
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/kernel/reporting.rb#L20" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-silence_warnings">
            
              silence_warnings(&amp;block)
            
          </h3>

          
            <div class="description">
              <p>Sets $VERBOSE to <code>nil</code> for the duration of the block and back to its original value afterwards.</p>

<pre><code>silence_warnings do
  value = noisy_call # no warning voiced
end

noisy_call # warning voiced
</code></pre>
            </div>
          

          

          

          
          
            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 14
  def silence_warnings(&amp;block)
    with_warnings(nil, &amp;block)
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/kernel/reporting.rb#L14" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-suppress">
            
              suppress(*exception_classes)
            
          </h3>

          
            <div class="description">
              <p>Blocks and ignores any exception passed as argument if raised within the block.</p>

<pre><code>suppress(ZeroDivisionError) do
  1/0
  puts &#39;This code is NOT reached&#39;
end

puts &#39;This code gets executed and nothing related to ZeroDivisionError was seen&#39;
</code></pre>
            </div>
          

          

          

          
          
            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 41
  def suppress(*exception_classes)
    yield
  rescue *exception_classes
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/kernel/reporting.rb#L41" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
        <div class="method">
          <h3 id="method-i-with_warnings">
            
              with_warnings(flag)
            
          </h3>

          
            <div class="description">
              <p>Sets $VERBOSE for the duration of the block and back to its original value afterwards.</p>
            </div>
          

          

          

          
          
            <details class="method__source">
              <summary>
                <span class="label">📝 Source code</span>
              </summary>

              <pre><code class="ruby"># File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 26
  def with_warnings(flag)
    old_verbose, $VERBOSE = $VERBOSE, flag
    yield
  ensure
    $VERBOSE = old_verbose
  end</code></pre>
              
                <a href="https://github.com/rails/rails/blob/dd8f7185faeca6ee968a6e9367f6d8601a83b8db/activesupport/lib/active_support/core_ext/kernel/reporting.rb#L26" target="_blank" class="github_url">🔎 See on GitHub</a>
              
            </details>
          
        </div>
        
      
    
  
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