2
我刚刚认识到,imp.reload()
不删除旧的类和函数,如果它们从模块的源文件中删除。为什么python的imp.reload()不会删除旧的类和函数?
为例:
:~$ python3
Python 3.2.3 (default, May 3 2012, 15:54:42)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> print(open("test.py").read())
# empty file
>>> import test
>>> dir(test)
['__builtins__', '__cached__', '__doc__', '__file__', '__name__',
'__package__']
>>> print(open("test.py").read())
# new class A and B added
class A:
pass
class B:
pass
>>> import imp
>>> dir(imp.reload(test))
['A', 'B', '__builtins__', '__cached__', '__doc__', '__file__', '__name__',
'__package__']
>>> print(open("test.py").read())
# class A deleted
class B:
pass
>>> dir(imp.reload(test))
['A', 'B', '__builtins__', '__cached__', '__doc__', '__file__', '__name__',
'__package__']
>>> import sys
>>> dir(sys.modules['test'])
['A', 'B', '__builtins__', '__cached__', '__doc__', '__file__', '__name__',
'__package__']
>>> sys.modules['test'].A
<class 'test.A'>
在最后几行可以看到,有一类对象A
虽然它是从模块的源代码被删除。这是为什么?有没有办法识别模块的这些元素?