C＃：抽象类中的抽象和非抽象方法？

Question

I am not sure whether the code I'm writing makes sense. Here's the general idea:

I have a Parser class that will take different types of documents. Depending on the type, I will parse the document differently.

So suppose I have two types of documents, A and B. The factory pattern seems like a pretty good way to go about doing this in case I need to extend the program to handle additional types, so I will have an abstract class.

abstract class Parser
{
   ...
   public void common_method() {
      // something common that all parsers will use
      // like file IO
   }

   // derived classes will override this
   public abstract void specific_method();
}

class A_Parser : Parser
{
   ...
}

class B_Parser : Parser
{
   ...
}

The issue I'm wondering about is the fact that I have declared abstract methods and non-abstract methods in my abstract Parser. Compiler doesn't seem to be complaining, and it still seems to work correctly.

Is this non-standard? Maybe there's a better way to design this?

Answer 1

This is perfectly fine. If you only had abstract methods, you'd have essentially an interface. You may have to use another pattern to create the actual instances of the parser if necessary, but as far as the class definition goes, this is pretty standard.

Answer 2

这非常好，您甚至可以制作一些非必须覆盖的virtual方法

Answer 3

This is the typical implementation of the Template Method Pattern . You provide the general pattern for algorithm but the details are implemented in concrete classes.

Answer 4

It is common to have non abstract method in abstract class.

You should also know that as your Parser class is abstract, the only way one can access common_method is via instance of A_Parser or B_Parser class.