enum是一個用來枚舉的模塊
import enum # 建立一個類,繼承自enum下的Enum class Color(enum.Enum): red = 1 green = 2 blue = 3 yellow = 4 pink = 5 cyan = 6 # 下面即可以經過名稱直接獲取成員 print(Color["red"], type(Color["red"])) # Color.red <enum 'Color'> print(Color.red, type(Color.red)) # Color.red <enum 'Color'> # 打印的是<enum 'Color'>類型 # 那麼如何獲取裏面的值呢? # 調用name獲取名稱,調用value獲取值 print(Color.red.name, type(Color.red.name)) # red <class 'str'> print(Color.red.value) # 1 # 也能夠經過迭代來獲取值 for c in Color: print(c.name, c.value) """ red 1 green 2 blue 3 yellow 4 pink 5 cyan 6 """
import enum # 若是我定義了重複的key(仮) try: class Color(enum.Enum): red = 1 green = 2 blue = 3 yellow = 4 pink = 5 cyan = 6 cyan = 5 except Exception as e: print(e) # Attempted to reuse key: 'cyan' # 提示咱們key重複了
import enum # 若是我定義了重複的value(仮) class Color(enum.Enum): red = 1 green = 2 blue = 3 yellow = 4 pink = 5 cyan = 6 purple = 6 # 這是經過value來獲取成員 # 獲取成員能夠經過Color.key | Color[key]的方式,還能夠使用Color(value)的方式 print(Color(6).name) # cyan print(Color.purple.name) # cyan # 能夠看到只打印了cyan # 若是值相同的話,那麼後者至關於前者的別名,二者指向的內容是同樣的 for c in Color: print(c) """ Color.red Color.green Color.blue Color.yellow Color.pink Color.cyan """ # purple依舊沒有打印 # 那若是我就想把值相同的也打印出來,要怎麼作呢? # 枚舉內部有一個__members__屬性,至關於一個字典 for c in Color.__members__.items(): print(c[0], c[1]) """ red Color.red green Color.green blue Color.blue yellow Color.yellow pink Color.pink cyan Color.cyan purple Color.cyan """ # 第一個元素是key,str類型。第二個元素是枚舉類型。 # 能夠看到最後一個,即使key是purple,可是對應的枚舉類型依舊是Color.cyan for c in Color.__members__.items(): print(c[0], c[1], c[1].name, c[1].value) """ red Color.red red 1 green Color.green green 2 blue Color.blue blue 3 yellow Color.yellow yellow 4 pink Color.pink pink 5 cyan Color.cyan cyan 6 purple Color.cyan cyan 6 """ # 最後一個打印的還是cyan # 成員以前也能夠進行比較,但只支持is和==操做符,不支持大小比較 print(Color.green is Color.red) # False print(Color.green is Color.green) # True print(Color.cyan is Color.purple) # True print(Color.cyan == Color.purple) # True
import enum class Color(enum.Enum): red = 1 green = 2 blue = 3 yellow = 4 pink = 5 cyan = 6 purple = 6 try: Color.red.name = "xxx" except Exception as e: print(e) # can't set attribute try: Color.red.value = "xxx" except Exception as e: print(e) # can't set attribute # 能夠看到是沒法賦值的
import enum class Color(enum.Enum): red = 1 green = 2 blue = 3 yellow = 4 pink = 5 cyan = [] purple = [] print(Color.cyan is Color.purple) # True Color.cyan.value.append(123) print(Color.cyan is Color.purple) # True """ 能夠看到,儘管沒法從新賦值,可是本地修改仍是能夠的,若是是可變類型的話 可是兩個仍是同樣的,由於purple是cyan的別名,當在建立這個類的時候,因爲都是空列表,因此認爲二者是同樣 所以當我對cyan.value進行append的時候,會影響purple """ print(Color.cyan.value) # [123] print(Color.purple.value) # [123] Color.purple.value.append(456) # 經過反過來也是同樣的 print(Color.cyan.value) # [123, 456] print(Color.purple.value) # [123, 456]
枚舉類,key重複是不容許的,可是值重複是能夠的,可若是我也不容許值重複呢?只須要加上一個裝飾器便可
python
import enum try: @enum.unique class Color(enum.Enum): red = 1 green = 2 blue = 3 yellow = 4 pink = 5 cyan = [] purple = [] except Exception as e: print(e) # duplicate values found in <enum 'Color'>: purple -> cyan # 提示咱們purple和cyan的value重複了
以前說過,枚舉成員是不支持大小比較的,但若是我想支持呢?
app
import enum # 換一種繼承的類,改爲IntEnum class Color(enum.IntEnum): red = 1 green = 2 blue = 3 yellow = 4 pink = 5 cyan = "6" # 此時裏面的成員要是int類型,或者能將字符串轉成int print(Color.red < Color.blue) # True print(Color.red + Color.cyan) # 7