TypeError Missing 1 required positional argument self

Question

I can t get past the error  Traceback  most recent call last     File  quot C  Users Dom Desktop test test py quot   line 7  in  lt module gt      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  quot init quot     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

User · Answer

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  quot The details of your account are  quot  self account number   self balance amount      object   class  passing values to constructor    p   Pump  quot Tahir quot  12000   p getPumps

User · Answer

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   quot init quot     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

User · Answer

You need to instantiate a class instance here   Use  p   Pump   p getPumps     Small example -    gt  gt  gt  class TestClass          def   init   self               print  in init           def testFunc self               print  in Test Func      gt  gt  gt  testInstance   TestClass   in init  gt  gt  gt  testInstance testFunc   in Test Func

User · Answer

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

User · Answer

You need to initialize it first   p   Pump   getPumps

User · Answer

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

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

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