[python] TypeError: Missing 1 required positional argument: 'self'

I can't get past the error:

Traceback (most recent call last):
  File "C:\Users\Dom\Desktop\test\test.py", line 7, in <module>
    p = Pump.getPumps()
TypeError: getPumps() missing 1 required positional argument: 'self'

I examined several tutorials but there doesn't seem to be anything different from my code. The only thing I can think of is that python 3.3 requires different syntax.

class Pump:

    def __init__(self):
        print("init") # never prints

    def getPumps(self):
        # Open database connection
        # some stuff here that never gets executed because of error
        pass  # dummy code

p = Pump.getPumps()

print(p)

If I understand correctly, self is passed to the constructor and methods automatically. What am I doing wrong here?

The self keyword in Python is analogous to this keyword in C++ / Java / C#.

In Python 2 it is done implicitly by the compiler (yes Python does compilation internally). It's just that in Python 3 you need to mention it explicitly in the constructor and member functions. example:

 class Pump():
 //member variable
 account_holder
 balance_amount

   // constructor
   def __init__(self,ah,bal):
   |    self.account_holder = ah
   |    self.balance_amount = bal

   def getPumps(self):
   |    print("The details of your account are:"+self.account_number + self.balance_amount)

 //object = class(*passing values to constructor*)
 p = Pump("Tahir",12000)
 p.getPumps()

You need to initialize it first:

p = Pump().getPumps()

You can also get this error by prematurely taking PyCharm's advice to annotate a method @staticmethod. Remove the annotation.

You can call the method like pump.getPumps(). By adding @classmethod decorator on the method. A class method receives the class as the implicit first argument, just like an instance method receives the instance.

class Pump:

def __init__(self):
    print ("init") # never prints

@classmethod
def getPumps(cls):
            # Open database connection
            # some stuff here that never gets executed because of error

So, simply call Pump.getPumps() .

In java, it is termed as static method.

Works and is simpler than every other solution I see here :

Pump().getPumps()

This is great if you don't need to reuse a class instance. Tested on Python 3.7.3.