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如何命名類變量

Python

炎炎設(shè)計(jì) 2022-06-22 18:19:28

是否有關(guān)于如何命名類變量的約定（與實(shí)例變量不同），或者沒(méi)有真正的區(qū)別。例如：import pymysqlclass DB: NUM_CONNECTIONS = 0 def __init__(self): self.conn = None self.cursor = None def __repr__(self): return 'Closed connection' if not self.conn else f'Open conection @ 0x{id(self):x}' def connect(self): if self.conn: return self.conn = pymysql.connect(host='127.0.0.1',user='root') self.cursor = self.conn.cursor() DB.NUM_CONNECTIONS += 1目前我通常將變量作為CLASS_VARIABLES和instance_variables。有哪些常見(jiàn)的模式？

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2 回答

慕斯王

TA貢獻(xiàn)1864條經(jīng)驗(yàn) 獲得超2個(gè)贊

讓我們檢查一下 pylint 對(duì)類變量名稱的看法?？紤]以下代碼示例：

# top-level constants for comparison

lowercase_var = 0

UPPERCASE_VAR = 1

CamelCaseVar = 2

def func():

# function local variables

lowercase_var2 = 0

UPPERCASE_VAR2 = 1

CamelCaseVar2 = 2

class ClassName:

# class variables

lowercase_var3 = 0

UPPERCASE_VAR3 = 1

CamelCaseVar3 = 2

pylint 的輸出：

D:\tmp>pylint test.py

************* Module test

test.py:1:0: C0103: Constant name "lowercase_var" doesn't conform to UPPER_CASE naming style (invalid-name)

test.py:3:0: C0103: Constant name "CamelCaseVar" doesn't conform to UPPER_CASE naming style (invalid-name)

test.py:8:4: C0103: Variable name "UPPERCASE_VAR2" doesn't conform to snake_case naming style (invalid-name)

test.py:9:4: C0103: Variable name "CamelCaseVar2" doesn't conform to snake_case naming style (invalid-name)

test.py:7:4: W0612: Unused variable 'lowercase_var2' (unused-variable)

test.py:8:4: W0612: Unused variable 'UPPERCASE_VAR2' (unused-variable)

test.py:9:4: W0612: Unused variable 'CamelCaseVar2' (unused-variable)

test.py:12:0: R0903: Too few public methods (0/2) (too-few-public-methods)

------------------------------------------------------------------

Your code has been rated at 2.73/10 (previous run: 1.82/10, +0.91)

觀察：

沒(méi)有關(guān)于三個(gè)類變量名稱中的任何一個(gè)的警告。這三個(gè)都是完全有效的。
大寫(xiě)名稱通常用于頂級(jí)常量?？梢詫?duì)類變量使用大寫(xiě)命名約定，使它們看起來(lái)像一個(gè)常量值。如果您正在修改變量DB.NUM_CONNECTIONS += 1，最好選擇另一種命名樣式。
snake_case 命名風(fēng)格用于函數(shù)局部變量名和函數(shù)名，CamelCase 僅用于類名。類變量是一個(gè)變量，它不是一個(gè)類（而是屬于一個(gè)類）。所以看起來(lái)最好選擇snake_case。

最后兩個(gè)意見(jiàn)是固執(zhí)己見(jiàn)的，您可以不同意并做出自己的選擇。好消息：您可以從三個(gè)選項(xiàng)中選擇任何一個(gè)。

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