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108 lines
1.4 KiB
Markdown
108 lines
1.4 KiB
Markdown
# 简介
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## 属性 attributes
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属性是与对象绑定的一组数据，可以只读，只写，或者读写，使用时不加括号，例如：
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In [1]:
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```py
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f = file("new_file", 'w')
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```
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显示模式属性：
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In [2]:
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```py
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f.mode
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```
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Out[2]:
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```py
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'w'
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```
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是否关闭：
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In [3]:
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```py
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f.closed
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```
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Out[3]:
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```py
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False
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```
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`mode` 是只读属性，所以这样会报错：
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In [4]:
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```py
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f.mode = 'r'
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```
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```py
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---------------------------------------------------------------------------
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TypeError Traceback (most recent call last)
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<ipython-input-4-d9757d46f855> in <module>()
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----> 1 f.mode = 'r'
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TypeError: readonly attribute
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```
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获取属性不需要加括号：
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In [5]:
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```py
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f.mode()
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```
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```py
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---------------------------------------------------------------------------
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TypeError Traceback (most recent call last)
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<ipython-input-5-6b67c2ae8f67> in <module>()
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----> 1 f.mode()
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TypeError: 'str' object is not callable
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```
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## 方法 method
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方法是与属性绑定的一组函数，需要使用括号，作用于对象本身：
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In [6]:
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```py
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f.write('Hi.\n')
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f.seek(0)
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f.write('Hola!\n')
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f.close()
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```
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In [7]:
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```py
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!rm new_file
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```
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## 使用 OPP 的原因
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* 构建自己的类型来模拟真实世界的对象
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* 处理抽象对象
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* 容易复用和扩展
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* 理解其他 OPP 代码
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* GUI 通常使用 OPP 规则编写
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* ... |