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Encapsulation

Encapsulation hides internal details and exposes a minimal interface. It prevents external code from depending on internal representation and helps maintain invariants.

class BankAccount:
    def __init__(self, balance=0):
        self._balance = balance  # underscore signals "private"

    def deposit(self, amount):
        if amount > 0:
            self._balance += amount

    def balance(self):
        return self._balance

classdef BankAccount
  properties (Access = private)
    balance = 0;
  end
  methods
    function obj = deposit(obj, amount)
      if amount > 0
        obj.balance = obj.balance + amount;
      end
    end
    function b = getBalance(obj)
      b = obj.balance;
    end
  end
end

Gotchas

  • Python's privacy is by convention (_ vs __ name mangling) — it does not enforce access.
  • Use property getters/setters when you need to validate assignments or compute values on access.
  • In Matlab, Access = private enforces visibility rules more strictly.