Class / Object in Python

Definition

• attribute := class.x or obj.x
• method := callable attribute
• variable/field := non-callable attribute

class Class:
  cls_var_a = ...
  cls_var_b: type                  # variable annotation
  cls_var_c: dict[type, type] = {} # variable annotation

  def obj_method(self[, ...]):
    self.obj_var = ...
    ...
    ...Class.cls_var_a...          # 在物件方法中調用類別屬性
    ...

  @classmethod
  def cls_method(cls[, ...]):
    ...

  @staticmethod                    # Doesn't receive self or cls
  def static_method([...]):
    ...

obj = Class([...])

Variable Annotation¹PEP 526 – Syntax for Variable Annotations – Global and local variable annotations²Python Docs: Annotated assignment statements

只有var: type時，不會建立其變數實體
僅記錄於__annotations__

Dynamic Attribute Assignment | Adding Attributes at Runtime | Monkey-Patching

a = A()

• a.new_attr = ...
• A.new_attr = ...
• from types import MethodType
a.new_obj_method = MethodType(..., a)
• A.new_cls_method = classmethod(...)
• A.new_static_method = staticmethod(...)

Last Updated on 2025/05/29 by A1go

References

• 1
  PEP 526 – Syntax for Variable Annotations – Global and local variable annotations
• 2
  Python Docs: Annotated assignment statements