Magic method
__eq__()比較是否相同
使用到 == 會呼叫 __eq__()
cat1 == cat2
以下程式碼，二個等號左邊 cat1 為 self ,等號右邊 cat2 為 other。
def __eq__(self, other):
def __eq__(本身物件, 要比較的物件):
def __eq__(cat1, cat2):
沒有覆寫__eq__()之前，比較的是記憶體位址。
完整程式碼
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class Cat:
def __init__(self, name, age):
self.name = name
self.age = age
def __eq__(self, other):
return self.name == other.name and self.age == other.age
cat1 = Cat("小咪",5)
cat2 = Cat("小咪",5)
print(f"cat1 == cat2 : {cat1 == cat2}")
cat1 == cat2 : True
斷行
使用圓括號斷行:
return (self.name == other.name and
self.age == other.age)
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class Cat:
def __init__(self, name, age):
self.name = name
self.age = age
def __str__(self):
return f"name: {self.name}, age: {self.age}"
def __eq__(self, other):
return (self.name == other.name and
self.age == other.age)
cat1 = Cat("小咪",5)
cat2 = Cat("小咪",5)
print(f"cat1 == cat2 : {cat1 == cat2}")
使用\斷行:
return self.name == other.name and \
self.age == other.age
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class Cat:
def __init__(self, name, age):
self.name = name
self.age = age
def __str__(self):
return f"name: {self.name}, age: {self.age}"
def __eq__(self, other):
return self.name == other.name and \
self.age == other.age
cat1 = Cat("小咪",5)
cat2 = Cat("小咪",5)
print(f"cat1 == cat2 : {cat1 == cat2}")
isinstance 判斷是否為某個類別
if isinstance(物件記憶體位址, 類別):
if isinstance(other, Cat):
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def __eq__(self, other):
# 判斷是否為相同類別
if isinstance(other, Cat):
return self.name == other.name and \
self.age == other.age
return False
__ne__() 不等於
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class Cat:
def __init__(self, name, age):
self.name = name
self.age = age
def __str__(self):
return f"name: {self.name}, age: {self.age}"
def __eq__(self, other):
if isinstance(other, Cat):
return self.name == other.name and \
self.age == other.age
return False
def __ne__(self, other):
return not self.__eq__(other)
class Dog:
def __init__(self, name, age):
self.name = name
self.age = age
cat = Cat("小咪", 5)
dog = Dog("小咪", 5)
print(f"cat != dog : {cat != dog}")
cat != dog : True
大於 小於
__lt__(self, other)小於x < y__le__(self, other)小於等於x <= y__gt__(self, other)大於x > y__ge__(self, other)大於等於x >= y
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class Cat:
def __init__(self, name, age):
self.name = name
self.age = age
def __str__(self):
return f"name: {self.name}, age: {self.age}"
def __eq__(self, other):
if isinstance(other, Cat):
return self.name == other.name and \
self.age == other.age
return False
def __ne__(self, other):
return not self.__eq__(other)
def __lt__(self, other):
if isinstance(other, Cat):
return self.age < other.age
return False
def __le__(self, other):
if isinstance(other, Cat):
return self.age <= other.age
return False
def __gt__(self, other):
if isinstance(other, Cat):
return self.age > other.age
return False
def __ge__(self, other):
if isinstance(other, Cat):
return self.age >= other.age
return False
cat1 = Cat("小咪", 5)
cat2 = Cat("小咪", 10)
print(f"cat1 < cat2 : {cat1 < cat2}")
print(f"cat1 <= cat2 : {cat1 <= cat2}")
print(f"cat1 > cat2 : {cat1 > cat2}")
print(f"cat1 >= cat2 : {cat1 >= cat2}")
cat1 < cat2 : True
cat1 <= cat2 : True
cat1 > cat2 : False
cat1 >= cat2 : False