[python] Python objects

Object

• (general meaning)
  • a material thing that can be seen and touched
• in programming
  • a combination of variables and functions that is in memory
• Everything in Python is an object
  • integers
  • strings
  • functions
  • files
  • etc.

A Python Integer is more than just an integer

The standard Python implementation is written in C. This means that every Python object is simply a cleverly disguised C structure, which contains not only its value, but other information as well. For example, when we define an integer in Python, such as x = 10000, x is not just a ‘raw’ integer. It’s actually a pointer to a compound C structure, which contains several values.

Python variables

Variables are labels that are attached to the objects. Variables are not objects nor containers for objects; they only act as a pointer or a reference to the object.

= 연산을 하면 단순히 값을 복사하는 것이 아니라, 가리키는 pointer 자체를 옮기는 것이다.

Immutable objects

• An immutable object cannot be changed after it is created
• Immutable objects in Python: int, float, string, etc.

• Reference link is broken if we assign a new object

Data types

• Each object has a data type (for example, int, float, etc.)
• The variable which points to the object does not have a specific type
  • No need to declare data types for variables

• python에서는 변수를 만들어서 데이터를 저장할 때 데이터 타입을 지정해 주지 않는다.
  • 우리가 저장하려는 데이터를 전달하면, 그 타입에 따라서 object가 만들어지고 그 object에 의해 data type이 결정 된다.
  • 그래서 변수라는 애는 단순히 그 object를 가리키는 reference로써 기능을 하기 때문에 data type이 없는 것이다.

• Each object has a data type, but variables don’t

Python Built-in Data types