title: Python: replacing a function within a class of a module
body: <p>I'm trying to replace a function defined within a class in order to modify its function (as in inner workings) without changing the actual code.
  I've never done this before, and, hence, am having some problems while replacing it.</p>
  <p>Changing the code will have me accessing the package within my Python library which is not much of an option.</p>
  <p>For example, if the module was called testMOD,</p>
  <pre><code>class testMOD(object):
      def testFunc(self, variable):
          var = variable
          self.something = var + 12
  </code></pre>
  <p>Then I would import testMOD, define a class (mytest =  testMOD()), and access the defined function within the class, testFunc, and change it to already defined function.</p>
  <p>For instance,</p>
  <pre><code>from somemodule import testMOD
  mytest = testMOD()
  
  def alternativeFunc(self, variable):
      var = variable
      self.something = var + 1.2
  
  # A problem here
  mytest.testFunc = alternativeFunc
  </code></pre>
  <p>As you can see, if I just manually overwrite(?) the function in the class with my defined function it won't work properly.</p>
  <p>It doesn't give any syntax errors, however, the problem is that the replaced function thinks that the 'self' is another variable for the function and says that it requires another argument for the 'variable' variable (I guess that wasn't a good name).</p>
  <p>I want to make the replacing function to be exactly the same thing as the replaced function, but with additional code or some minor modifications. However, the 'self' is pretty much not working as it should be in a class.</p>
  <p>Would there be a way to properly implement a defined function to replace a function of an imported class?</p>