How to assign an operation like sum or substitute, etc., to a variable
<p>I want to do something like</p>

<pre><code>class A:
    def __init__( self, left, right, op ):
        self.left = left
        self.right = right
        self.op = op
    def calculate( self ):
        self.number = op( self.left, self.right )
        return self.number
</code></pre>

<p>and use it, for example, like this:</p>

<pre><code>a = A( 1, 2, + )
a2 = A( 2, 3, * )
</code></pre>

<p>I tried to do</p>

<pre><code>op = +
op = __add__
</code></pre>

<p>but none of these worked. Can somebody tell is this possible (and if it is, how this is called, because I don't even know how to search it). Or the only possible way is to have a big, ugly <code>if-else</code> statement in <code>calculate</code> and check the value of <code>op</code>, which will be stored as <code>str</code>?</p>

<p>Thanks!</p>
