CODEWITHSUNDEEP
pythonclasspython-3.xobjectinitialization
user6003691
user6003691

Reputation:

Object variable of a class as a tuple

I am trying to define an object variable of a class so that it would be a tuple as seen below:

class MyClass(object):
    def __init__(self):
        self.results = ? # tuple

    def generate_results(self, a):
        # tuple to hold the 3 result integers
        self.results = (self.calculate_first_result(a),  
                        self.calculate_second_result(a),
                        self.calculate_third_result(a))

(where the calculate_first_result, calculate_second_result and calculate_third_result are static methods of MyClass which perform some calculations and return an int)

I do not understand how the self.results in __init__ should be defined in order for it to hold the tuple with the 3 integers as it is calculated in generate_results method.

I am new with the class and object variable concepts in Python so any shortcomings in my design and approach will be appreciated.

Upvotes: 0

Views: 5963

Answers (1)

Billal BEGUERADJ
Billal BEGUERADJ

Reputation: 22754

You can optionally code this:

def __init__(self):
        self.results = ()

If I judge just from your code, I may say it is not important because inside generate_results() you overrided self.results.

It can be useful to initialize the empty tuple only if you need to keep a trace of it for further needs in your program, otherwise not.

The following code summerizes what I said:

class Begueradj:
   def __init__(self):       
       self.results = ()       

   def generate_results(self):
       self.results = (1,2,3) 
       print ' inside generate_results():    '+str(self.results)

   def display(self):
       print ' inside display():    '+str(self.results)


# Main program starts here   
if __name__ =='__main__':

   b = Begueradj()
   b.display() # This line will not work if you do not run self.results = () inside __init__()
   b.generate_results()
   b.display()

If you do not need to keep a track of self.results, meaning in our code sample that you do not need to call display() just before generate_results() method, then this will lead us to what @juanpa.arrivillaga commented you: I mean, it will become useless to initialize the empty tuple. The code below reflects this situation:

class Begueradj:
   def __init__(self): 
       # Do not do anything
       # We do not need to keep a track of self.results      
       pass       

   def generate_results(self):
       self.results = (1,2,3) 
       print ' inside generate_results():    '+str(self.results)

   def display(self):
       print ' inside display():    '+str(self.results)


# Main program starts here   
if __name__ =='__main__':

   b = Begueradj()
   # b.display() you can no longer call display() here as we did not initialize self.results inside __init__
   b.generate_results()
   b.display()

Upvotes: 1

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