CODEWITHSUNDEEP
pythonclassstatic-methodsstatic-variables
ai2016
ai2016

Reputation: 3101

Populate once static variable from static method Python within a class

I have a Class A in Python and I would like to populate the a static variable calling a static method like:

Class A:
   arr = []

   @staticmethod
   def FillArr():
       #do more stuff but for semplicity...
       A.arr = [[2,2,2,]]

  FillArr.__func__()

when I run the code I got 'NameError: name A not defined' so essentially I can't initialize the arr static variable. Essentially once the the class has been instantiated once I would like to populate the static variable

Upvotes: 1

Views: 2466

Answers (2)

Nemelis
Nemelis

Reputation: 5472

Use @classmethod:

class A(object):
  arr = []

  @classmethod
  def FillArr(cls):
    cls.arr = [[2,2,2]]

A.FillArr()

print A.arr

This will result in: [[2,2,2]]

/edit/ the using normal method example I mention in my comment below (based on Jacques explanation):

class A
   arr=[]

   def FillArr(self):
     self.arr = [[2,2,2,]]

   def __init__(self):
     self.FillArr()

a = A()
print a.arr

Upvotes: 2

Jacques de Hooge
Jacques de Hooge

Reputation: 7000

This runs flawlessly on Python 3.6:

class A:
   arr = []

   @staticmethod
   def fillArr():
       #do more stuff but for simplicity...
       A.arr = [[2,2,2,]]

A.fillArr()

print (A.arr)

Or, with the extra info in your comment:

class A:
    arr = []

    @staticmethod
    def fillArr():
        #do more stuff but for simplicity...
        A.arr = [[2,2,2,]]

    def __init__ (self):
        if not A.arr:
           A.fillArr ()

A ()

print (A.arr)

Upvotes: 3

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