Python 蟒蛇3‘内置’并不总是‘内置’__`
我正在为python3实施这个想法。 并且懒得使用变量Python 蟒蛇3‘内置’并不总是‘内置’__`,python,python-3.x,Python,Python 3.x,我正在为python3实施这个想法。 并且懒得使用变量\uuuuuuuuuu而不是模块内置。这应该没有什么区别,因为: # file spam.py: import builtins print (builtins is __builtins__) print (id(builtins)) print (id(__builtins__)) 有趣的是:builtins在导入时不是\uuuu builtins\uuuu: $ python3 spam.py True 14059800174333
\uuuuuuuuuu
而不是模块内置
。这应该没有什么区别,因为:
# file spam.py:
import builtins
print (builtins is __builtins__)
print (id(builtins))
print (id(__builtins__))
有趣的是:builtins
在导入时不是\uuuu builtins\uuuu
:
$ python3 spam.py
True
140598001743336
140598001743336
$ python3 -c 'import spam'
False
139755426543080
139755426520904
有人知道会发生什么吗
(给定页面上的一条评论提到,“
\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu>是一个CPython特性,你真的不应该使用它”,但我很好奇
框架全局变量有一个\uuuu内置变量
变量(内置字典,或
当\uuuu name\uuuuu
等于\uuuuu main\uuuu
时的内置模块
因此,在第一种情况下(\uuuu name\uuuuu==\uuuuu main\uuuuuu
),您得到\uuuuuuuu内置的作为内置的
模块,但在第二种情况下(\uuuu name\uuuuuuuuuu!=\uuu main\uuuuuuu
)\uuuu内置的
是一个实例,来自:
\uuuu内置\uuuu
的值通常是此模块或值
此模块的\uuuu dict\uuuu
属性
试验
使用稍微修改的spam.py
import builtins
if __name__ == '__main__':
print(type(__builtins__))
print(__builtins__ is builtins)
print(id(builtins))
print(id(__builtins__))
else:
print(type(__builtins__))
print(__builtins__ is builtins.__dict__)
print(id(builtins.__dict__))
print(id(__builtins__))
我们会得到类似于
$ python3 spam.py
<class 'module'>
True
2345652270648
2345652270648
$ python3 -c 'import spam'
<class 'dict'>
True
2770543697736
2770543697736
$python3 spam.py
真的
2345652270648
2345652270648
$python3-c“导入垃圾邮件”
真的
2770543697736
2770543697736
结论
正如您和切普纳已经注意到的那样,\uuuuuuuuuuuuuuuuuuuuuuuuuuu
是一个可以更改的实现细节,因此我们不应该依赖它,特别是它是一个内置模块/内置对象。对于CPython实现
在\uuuu main\uuuuuuu
模块中:\uuuuu内置\uuuuuuuuuu是内置的
在其他模块中:\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
参考文献:
\uuuuuuuuuuuuuuuuuuuuuuuuuuu
是一个具体的实现细节,因此您不应该依赖它。