coding-mentor-agent/kb/python-course-kb-practical-python/wiki/exercises/5-5-inheritance.md

id, source_exercise_id, title, section, source_path, source_repo, source_commit, student_visible_solution, has_private_solution, skip

id	source_exercise_id	title	section	source_path	source_repo	source_commit	student_visible_solution	has_private_solution	skip
practical-python-5.5	5.5	Inheritance	5.1 Dictionaries Revisited	05_Object_model/01_Dicts_revisited.md	https://github.com/dabeaz-course/practical-python	93dca856b41c61a0a0f85ae334116e4c125629ea	false	false	false

Exercise 5.5: Inheritance

Source: Practical Python Programming, 05_Object_model/01_Dicts_revisited.md.

Exercise 5.5: Inheritance

Make a new class that inherits from Stock.

>>> class NewStock(Stock):
        def yow(self):
            print('Yow!')

>>> n = NewStock('ACME', 50, 123.45)
>>> n.cost()
6172.50
>>> n.yow()
Yow!
>>>

Inheritance is implemented by extending the search process for attributes. The __bases__ attribute has a tuple of the immediate parents:

>>> NewStock.__bases__
(<class 'stock.Stock'>,)
>>>

The __mro__ attribute has a tuple of all parents, in the order that they will be searched for attributes.

>>> NewStock.__mro__
(<class '__main__.NewStock'>, <class 'stock.Stock'>, <class 'object'>)
>>>

Here's how the cost() method of instance n above would be found:

>>> for cls in n.__class__.__mro__:
        if 'cost' in cls.__dict__:
            break

>>> cls
<class '__main__.Stock'>
>>> cls.__dict__['cost']
<function cost at 0x101aed598>
>>>

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关联来源

• summaries/01_Dicts_revisited