title: Python - Execute a String Code For Fractions
body: <p>I've been working in some type of calculator for fractions using <code>from fractions import *</code> following the next logic:</p>
  
  <pre><code>a = Fraction(1,4)
  b = Fraction(2,5)
  c = Fraction(3,4)
  
  print(a+b*c)
  </code></pre>
  
  <p><strong>OUTPUT</strong></p>
  
  <pre><code>11/20
  </code></pre>
  
  <p>But I need to execute the statement from a string, just like <code>1/4 + 1/2</code> and for some reason always returns me <strong>0</strong> or <strong>1</strong>:</p>
  
  <pre><code>from fractions import *
  
  class main():
      for i in range(0, 10):
          print "\t\nWRITE YOUR OPERATION"
          code = 'print('
          s = raw_input()
          elements = s.split()
  
          for element in elements:
              print(element)
  
              if '/' in element:
                  fraction = element.split('/')
                  numerator = fraction[0]
                  denominator = fraction[1]
                  a = Fraction(int(numerator),int(denominator))
                  code = code + str(a)
              else:
                  code = code + str(element)                
  
          code = code + ')'        
  
          exec code
  </code></pre>
  
  <p>It's something I'm missing? </p>
  
  <p><strong>EDIT 1</strong></p>
  
  <p>I know what is wrong here</p>
  
  <p>The string code is like this:</p>
  
  <pre><code>code = 'print(1/4+2/5*3/4)'
  </code></pre>
  
  <p>But what I really need is this (which I think is imposible to do):</p>
  
  <pre><code>code = 'print(Fraction(1,4)+Fraction(2,5)*Fraction(3,4))'
  </code></pre>
  
  <p>Or there is a way to do something like this...?</p>