python调试

print调试

之后出一篇python的log使用文章

下载：pip install pysnooper
导入使用

from pysnooper import snoop
""" watch：关注属性，注意，watch是个元组；
depth：递归深度，默认为1
"testsnooplog.txt"把snoop追加输出到log文件中，可不填，默认输出到控制台
watch_explode：展开输出字典的值，个人感觉没啥用"""
@snoop("testsnooplog.txt", watch=("oTestA.m_Num",), depth=2)
def DoMain():
    oTestA = CTestA()
    oTestA.m_Num = 3            # 测试关注属性的变化
    print(oTestA.m_Num)
    # 测试字典变量追踪
    dTempDict = {1: 1, 2: 2}
    dTempDict[1] = 3            # 变量更改也会打印
    if 1:
        iTemp = GetSum(1, 2)    # 测试递归深度
    del oTestA.m_Num

"testsnooplog.txt“中的内容如下

Source path:... D:/study/python/pycode/python_study/调试.py
22:04:16.486441 call        24 def DoMain():
22:04:16.499442 line        25     oTestA = CTestA()
    Starting var:.. self = <__main__.CTestA object at 0x01C04950>
    22:04:16.506444 call         5     def __init__(self):
    22:04:16.518447 line         6         self.m_Num = 1
    22:04:16.524947 return       6         self.m_Num = 1
    Return value:.. None
New var:....... oTestA = <__main__.CTestA object at 0x01C04950>
New var:....... oTestA.m_Num = 1
22:04:16.536450 line        26     oTestA.m_Num = 3            # 测试关注属性的变化
Modified var:.. oTestA.m_Num = 3
22:04:16.555453 line        27     print(oTestA.m_Num)
22:04:16.567956 line        29     dTempDict = {1: 1, 2: 2}
New var:....... dTempDict = {1: 1, 2: 2}
22:04:16.573956 line        30     dTempDict[1] = 3            # 变量更改也会打印
Modified var:.. dTempDict = {1: 3, 2: 2}
22:04:16.586458 line        32         iTemp = GetSum(1, 2)    # 测试递归深度
    Starting var:.. iNumA = 1
    Starting var:.. iNumB = 2
    22:04:16.598461 call        36 def GetSum(iNumA, iNumB):
    22:04:16.616965 line        37     return iNumA + iNumB
    22:04:16.622965 return      37     return iNumA + iNumB
    Return value:.. 3
New var:....... iTemp = 3
22:04:16.633466 line        33     del oTestA.m_Num
22:04:16.645969 return      33     del oTestA.m_Num
Return value:.. None
Elapsed time: 00:00:00.171530

在更改某个实例的属性的时候，会调用__setattr__方法，
通过__setattr__我们可以追踪某个属性的更改，查看属性在什么时候被更改了
测试代码如下，类被初始化的时候调用一次__setattr__，更改的时候调用一次，总共两次

class CTestA(object):
    def __init__(self):
        self.m_Num = 1

    def __setattr__(self, key, value):
        if hasattr(self, key):
            print("the attribute {} changed from {} to {}".format(key, self.__getattribute__(key), value))
        else:
            print("the attribute {} changed to {}".format(key, value))
        super(CTestA, self).__setattr__(key, value)


if __name__ == "__main__":
    oTestA = CTestA()
    oTestA.m_Num = 3
    print(oTestA.m_Num)

输出如下

D:studypython3.6.8python.exe D:/study/python/pycode/python_study/调试.py
the attribute m_Num changed to 1
the attribute m_Num changed from 1 to 3
3

Process finished with exit code 0

同2，在属性被删除的时候调用
在上面CTestA重写如下方法

    def __delattr__(self, item):
        print("the item {} has being delete".format(item))
        super(CTestA, self).__delattr__(item)

然后再main中调用del oTestA.m_Num
输出如下

D:studypython3.6.8python.exe D:/study/python/pycode/python_study/调试.py
the attribute m_Num changed to 1
the attribute m_Num changed from 1 to 3
3
the item m_Num has being delete

Process finished with exit code 0