精通ASP.NET（基于VB.NET)(四）VB.NET继承
（1） 理解继承：继承是实现相关类方法、接口等共享的一种手段。相关类是指类及其派生类。基于不同类实例的独特性，故引入了public、private、protected作用域和overrides(重写)、方法重载overloads。这样作的目的：提高代码的复用性。
（2）继承的种类：实现继承、接口继承和可视继承。
（3）接口：先看一例
Interface Inter_comm
sub read_x(by vlue x as integer)
Function write_x(by vlue x as integer) as long
Property pr_x() as string
end interface
class Inter_comm_made
Implements Inter_comm
private x as string
sub read_x(by vlue x as integer) Implements Inter_comm.read_x
end sub
Function write_x(byval x as integer) as long Implements Inter_comm.write_x
end function
Property pro_x() as string Implements Inter_comm.pr_x
get
return x
end get
set(byval value as string)
x=value
end set
end class
接口定义用Interface。实现用类或结构，用Implements指定。
