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Ruby

Extending Ruby Class Functions

#!/usr/bin/env ruby

require 'pry'

class Foo
  def bar
    puts "old_bar"
    2
  end
end


class Module
  def do_override(meth, name, &blk)
    @@override ||= {}
    @@override[:meth] ||= []
    class_exec(instance_method(meth)) do |mv|
      define_method(meth) do |*args|
        blk.call(mv.bind(self), *args)
      end
    end
    @@override[:meth] << name
  end

  def get_override_list(meth)
    return [] unless @@override
    @@override[:meth] || []
  end
end


#Foo.class_exec(Foo.instance_method(:bar)) do |v|
#  puts "Extending bar method"
#  define_method(:bar) do
#    puts "new_bar"
#    v.bind(self).call + 1
#  end # define_method
#end


binding.pry
https://snipt.net/embed/f3b4d6e080868a79d733f3b8b752ae2e/
/raw/f3b4d6e080868a79d733f3b8b752ae2e/
f3b4d6e080868a79d733f3b8b752ae2e
rb
Ruby
42
2019-07-15T20:03:34
True
False
False
Oct 31, 2012 at 03:59 PM
/api/public/snipt/49382/
extending-ruby-class-functions
<table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><a href="#L-1"> 1</a> <a href="#L-2"> 2</a> <a href="#L-3"> 3</a> <a href="#L-4"> 4</a> <a href="#L-5"> 5</a> <a href="#L-6"> 6</a> <a href="#L-7"> 7</a> <a href="#L-8"> 8</a> <a href="#L-9"> 9</a> <a href="#L-10">10</a> <a href="#L-11">11</a> <a href="#L-12">12</a> <a href="#L-13">13</a> <a href="#L-14">14</a> <a href="#L-15">15</a> <a href="#L-16">16</a> <a href="#L-17">17</a> <a href="#L-18">18</a> <a href="#L-19">19</a> <a href="#L-20">20</a> <a href="#L-21">21</a> <a href="#L-22">22</a> <a href="#L-23">23</a> <a href="#L-24">24</a> <a href="#L-25">25</a> <a href="#L-26">26</a> <a href="#L-27">27</a> <a href="#L-28">28</a> <a href="#L-29">29</a> <a href="#L-30">30</a> <a href="#L-31">31</a> <a href="#L-32">32</a> <a href="#L-33">33</a> <a href="#L-34">34</a> <a href="#L-35">35</a> <a href="#L-36">36</a> <a href="#L-37">37</a> <a href="#L-38">38</a> <a href="#L-39">39</a> <a href="#L-40">40</a> <a href="#L-41">41</a></pre></div></td><td class="code"><div class="highlight"><pre><span></span><span id="L-1"><a name="L-1"></a><span class="ch">#!/usr/bin/env ruby</span> </span><span id="L-2"><a name="L-2"></a> </span><span id="L-3"><a name="L-3"></a><span class="nb">require</span> <span class="s1">&#39;pry&#39;</span> </span><span id="L-4"><a name="L-4"></a> </span><span id="L-5"><a name="L-5"></a><span class="k">class</span> <span class="nc">Foo</span> </span><span id="L-6"><a name="L-6"></a> <span class="k">def</span> <span class="nf">bar</span> </span><span id="L-7"><a name="L-7"></a> <span class="nb">puts</span> <span class="s2">&quot;old_bar&quot;</span> </span><span id="L-8"><a name="L-8"></a> <span class="mi">2</span> </span><span id="L-9"><a name="L-9"></a> <span class="k">end</span> </span><span id="L-10"><a name="L-10"></a><span class="k">end</span> </span><span id="L-11"><a name="L-11"></a> </span><span id="L-12"><a name="L-12"></a> </span><span id="L-13"><a name="L-13"></a><span class="k">class</span> <span class="nc">Module</span> </span><span id="L-14"><a name="L-14"></a> <span class="k">def</span> <span class="nf">do_override</span><span class="p">(</span><span class="n">meth</span><span class="p">,</span> <span class="nb">name</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">blk</span><span class="p">)</span> </span><span id="L-15"><a name="L-15"></a> <span class="vc">@@override</span> <span class="o">||=</span> <span class="p">{}</span> </span><span id="L-16"><a name="L-16"></a> <span class="vc">@@override</span><span class="o">[</span><span class="ss">:meth</span><span class="o">]</span> <span class="o">||=</span> <span class="o">[]</span> </span><span id="L-17"><a name="L-17"></a> <span class="n">class_exec</span><span class="p">(</span><span class="nb">instance_method</span><span class="p">(</span><span class="n">meth</span><span class="p">))</span> <span class="k">do</span> <span class="o">|</span><span class="n">mv</span><span class="o">|</span> </span><span id="L-18"><a name="L-18"></a> <span class="n">define_method</span><span class="p">(</span><span class="n">meth</span><span class="p">)</span> <span class="k">do</span> <span class="o">|*</span><span class="n">args</span><span class="o">|</span> </span><span id="L-19"><a name="L-19"></a> <span class="n">blk</span><span class="o">.</span><span class="n">call</span><span class="p">(</span><span class="n">mv</span><span class="o">.</span><span class="n">bind</span><span class="p">(</span><span class="nb">self</span><span class="p">),</span> <span class="o">*</span><span class="n">args</span><span class="p">)</span> </span><span id="L-20"><a name="L-20"></a> <span class="k">end</span> </span><span id="L-21"><a name="L-21"></a> <span class="k">end</span> </span><span id="L-22"><a name="L-22"></a> <span class="vc">@@override</span><span class="o">[</span><span class="ss">:meth</span><span class="o">]</span> <span class="o">&lt;&lt;</span> <span class="nb">name</span> </span><span id="L-23"><a name="L-23"></a> <span class="k">end</span> </span><span id="L-24"><a name="L-24"></a> </span><span id="L-25"><a name="L-25"></a> <span class="k">def</span> <span class="nf">get_override_list</span><span class="p">(</span><span class="n">meth</span><span class="p">)</span> </span><span id="L-26"><a name="L-26"></a> <span class="k">return</span> <span class="o">[]</span> <span class="k">unless</span> <span class="vc">@@override</span> </span><span id="L-27"><a name="L-27"></a> <span class="vc">@@override</span><span class="o">[</span><span class="ss">:meth</span><span class="o">]</span> <span class="o">||</span> <span class="o">[]</span> </span><span id="L-28"><a name="L-28"></a> <span class="k">end</span> </span><span id="L-29"><a name="L-29"></a><span class="k">end</span> </span><span id="L-30"><a name="L-30"></a> </span><span id="L-31"><a name="L-31"></a> </span><span id="L-32"><a name="L-32"></a><span class="c1">#Foo.class_exec(Foo.instance_method(:bar)) do |v|</span> </span><span id="L-33"><a name="L-33"></a><span class="c1"># puts &quot;Extending bar method&quot;</span> </span><span id="L-34"><a name="L-34"></a><span class="c1"># define_method(:bar) do</span> </span><span id="L-35"><a name="L-35"></a><span class="c1"># puts &quot;new_bar&quot;</span> </span><span id="L-36"><a name="L-36"></a><span class="c1"># v.bind(self).call + 1</span> </span><span id="L-37"><a name="L-37"></a><span class="c1"># end # define_method</span> </span><span id="L-38"><a name="L-38"></a><span class="c1">#end</span> </span><span id="L-39"><a name="L-39"></a> </span><span id="L-40"><a name="L-40"></a> </span><span id="L-41"><a name="L-41"></a><span class="nb">binding</span><span class="o">.</span><span class="n">pry</span> </span></pre></div> </td></tr></table>
"class function", extend, ruby, super