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the Python programming can be achieved in raise report an error function, and error conditions can be customized by the programmers themselves go. In object-oriented programming, a method may be reserved first interface is not implemented, achieve its subclasses.
If it requires a subclass must be achieved, not when implemented it will lead to problems, so the way to raise the use of good.
The problem this time is generated classification NotImplementedError.
Write a piece of code as follows:
class ClassDemo:
def test_demo(self):
raiseNotImplementedError("my test: not implemented!")
classChildClass(ClassDemo):
pass
inst =ChildClass()
inst.test_demo()
Result of the program:
E:\01_workspace\02_programme_language\03_python\OOP\2017\08\10>pythonerror_demo.py
Traceback (mostrecent call last):
File "error_demo.py", line 9, in<module>
inst.test_demo()
File "error_demo.py", line 3, intest_demo
raise NotImplementedError("my test:not implemented!")
NotImplementedError:my test: not implemented!
As seen from the results of the above operation, the program identifies this method was not implemented in a subclass called.
From the point of view given the number of lines of code, only instantiate an object of this subclass when calling the appropriate method will be given.
Such a conclusion can be easily estimated by a modified test code is verified, here is no longer verified.
Further modify the code:
class ClassDemo:
def test_demo(self):
raiseNotImplementedError("my test: not implemented!")
classChildClass(ClassDemo):
def test_demo(self):
print("OKOKOOK!")
inst =ChildClass()
inst.test_demo()
In the new code, subclass implements test_demo design method.
Operating results of the program are as follows
E:\01_workspace\02_programme_language\03_python\OOP\2017\08\10>pythonerror_demo.py
OKOKOOK!
As seen from the results of execution of a program, as long as the corresponding interface method of implementation, an error in the implementation of the embodiment will not not reported.
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