从派生 class 到基础 class 的转换正在扩大？为什么？
Conversion from derived class to it's base class is widening? Why?
根据页面
https://msdn.microsoft.com/en-us/library/k1e94s7e.aspx
从派生 class 到基础 class 的转换正在扩大。我认为这是相反的：它正在缩小转换范围。因为基础 class 对象是派生 class 对象的一部分。
如何详细解释这是扩大转换？
来自您链接的页面：
It might seem surprising that a conversion from a derived type to one of its base types is widening. The justification is that the derived type contains all the members of the base type, so it qualifies as an instance of the base type. In the opposite direction, the base type does not contain any new members defined by the derived type.
根据页面
https://msdn.microsoft.com/en-us/library/k1e94s7e.aspx
从派生 class 到基础 class 的转换正在扩大。我认为这是相反的：它正在缩小转换范围。因为基础 class 对象是派生 class 对象的一部分。
如何详细解释这是扩大转换？
来自您链接的页面：
It might seem surprising that a conversion from a derived type to one of its base types is widening. The justification is that the derived type contains all the members of the base type, so it qualifies as an instance of the base type. In the opposite direction, the base type does not contain any new members defined by the derived type.