Getter & Setter

• Do not need to necessarily define them.
• If you need them you can add them.

[!NOTE]

Jargon time:

• Getter: a method for getting the value of a data attribute.
• Setter: a method for setting the value of a data attribute.

class User:
    """ Create a user and determine their email provider """

    def __init__(self):
        self._email = ''
        self._email_provider = ''

    def _get_email(self) -> str:
        return self._email

    def _set_email(self, email: str) -> None:
        if email.endswith("@gmail.com"):
            self._email_provider = 'Google'
        elif email.endswith("@yahoo.com"):
            self._email_provider = 'Yahoo'
        else:
            self._email_provider = "unknown"

        self._email = email

    email = property(_get_email, _set_email)

• property([fget=None, fset=None, fdel=None, doc=None]) function:

  • Defines properties.
  • A built-in function for creating and returning a property object.
    • A class with a function-like name.
  • Attach implicit getter and setter methods to given class attributes.
  • Python automatically calls the setter getter method when we try to assign a value to it or read from it respectively.

  Argument	Description
  fget	The method that returns the value of the data attribute.
  fset	The method that allows you to set the value of the data attribute.
  fdel	The method that defines how the data attribute handles deletion.
  doc	A string representing the property’s docstring.

• property() function can be used as a decorator as well. Making it a supernova :star_struck:.

  class User:
      """ Create a user and determine their email provider """
      def __init__(self):
          self._email = None
          self._email_provider = None
      @property
      def email(self) -> str:
          return self._email
      @email.setter
      def email(self, email: str) -> None:
          if email.endswith("@gmail.com"):
              self._email_provider = 'Google'
          elif email.endswith("@yahoo.com"):
              self._email_provider = 'Yahoo'
          else:
              self._email_provider = "unknown"
          self._email = email
      @email.deleter
      def email(self):
          del self._email
          del self._email_provider
      def print_me(self):
          if hasattr(self, '_email'):
              print(self._email, end='\t')
          if hasattr(self, '_email_provider'):
              print(self._email_provider, end='')
          print()
  u = User()
  u.email = 'asdasd@asdas.com'
  u.print_me()
  del u.email
  u.print_me()
  

Ref

• Python’s property(): Add Managed Attributes to Your Classes.

YouTube/Aparat

• https://youtu.be/ZrBn4XPyFuQ.
• https://aparat.com/v/hbu4c70.