CODEWITHSUNDEEP
python
usr784638
usr784638

Reputation: 97

Reuse a class's method in the main.py

I've searched a lot about how to reuse a method from a class in the main.py file. i got some similar and basic solutions but in my case is a bit different.

/lib/module.py

class Myclass:
    def __init__(self, x):
        self.thisX = x

    def check(self):
        if self.thisX == 2:
            print("this is fine. going to print it")
            self.printing()

    # this method will use in this class and must use from the main.py
    # the parameter "z" is gonna use only when the method will call from main.py
    def printing(self, z):
        if z == 1 :
            print("we got ", z)
        else:
            print(self.x)

/main.py

from lib.module import Myclass

# this is how i use the check() method once in my main.py
Myclass(2).check()

# the Myclass() gets "2" only once at the beginning of the program...
# i don't wanna pass "2" to the Myclass() everytime that i wanna use the printing() method...
c = Myclass()
c.printing(1)

error

TypeError: __init__() missing 1 required positional argument: 'x'

testing:

if i don't use the def init(), everything will be fine. but the problem is i need to keep it

Upvotes: 1

Views: 66

Answers (2)

Zheng Liu
Zheng Liu

Reputation: 302

I think @richflow 's answer hit the point. If some variable is to be shared by all instances of a class, it's logical to assign its value using Myclass.x = new_number. Then all instances of this class will know the change. If you really want to optionally change x in the __init__ method of an instance, you can still do it. Combining with @richflow's codes, it can look like the following.

class Myclass:
      x = 0
      def __init__(self, x=None):
        if x is not None:
          Myclass.x = x
          # other codes for initializiing the instance

      def check(self):
        if Myclass.x == 2:
          print("this is fine. going to print it")

      def printing(self, z=0):
            if z == 1 :
                print("we got ", z)
            else:
                print(Myclass.x)

I tried not to change too much from your codes. Your main.py should work correctly with this class definition. However, the design looks a bit weird to me. Probably that's because I didn't understand clearly what the check and printing methods are really doing, and what the argument z is really doing in printing methods. If you provides more insights, probably people can help you with a better design.

Upvotes: 0

richflow
richflow

Reputation: 2144

This line in main.py:

c = Myclass()

Calls this function:

class Myclass:
    def __init__(self, x):
        self.thisX = x

Every time you create an instance of Myclass it will call the __init__() function. You declared it to take 2 arguments: self and x. self is always passed implicitly because it's a class, but you need to give it an argument 'x'.

So you can change main.py to this for example:

c = Myclass(2) # here x = 2
c.printing(1)

Please read this for more information

Also, in general, class names are written in CapWords style so it's a good idea to call your class MyClass instead of Myclass

Edit:

Since you don't want to pass x to __init__() and you want to set x from main.py you can try something like this:

class Myclass:
  x = 0
  def check(self):
    if self.x == 2:
      print("x is 2")

from main.py you can do:

Myclass.x = 2; #this only needs to be done once
Myclass().check()

Output:

x is 2

Upvotes: 1

Related Questions