Question

I want my site to support different subscription types, free, premium and etc.

So far I made an abstract class that is like this

  public abstract class Limits
    {

        public int PostLimit { get; protected set; }


        protected Limits(int postLimit)
        {
            PostLimit = postLimit;
        }

        public bool IsLimitReached(int postCount)
        {
            return postCount > PostLimit 
        }

    }


 public class FreeLimit : Limits
    {
        private const int postLimit = 1;


        public FreeLimit()
            : base(postLimit)
        {
        }

    } 

So now I did this for all my account types. Now the problem is I don’t know how to actually use this class.

For instance I have a service layer call PostService and in this class I have

public void CreatePost(Post post)
{
  // do stuff here
}

Now in this method I don’t know how to check if they reached the limit. I don’t know how to check because I am unsure how to find out if I should be using the FreeLimit or PremiumLimit or what account they have.

I am thinking that I first have to figure out their Role and then somehow use that information to create the right class.

I guess I could have something like

public void CreatePost(Post post, PlanType planType)
{
   Limits limit;
   switch(planType)
   {
      case planType.Free:
         limit = new FreeLmit()
        break;
   }

    if(limit.IsLimitReached())
    {
      // do stuff
    }
} 

I don’t like this way as now for every method that needs to check a limit will have to do this. I will have a few methods that require this check in my service layer.

So I was thinking of putting it in my constructor but I don’t know if it is good to have a switch statement in a constructor.

Answer 1

You could use an interface ILimit

interface ILimit
{
    int PostLimit { get; protected set; }
    bool IsLimitReached(int postCount);
}

Now you can have several other classes (Free, Premium, Super) that implement this interface. In your service method CreatePost you can just pass any instance of a class that implements the interface and use it – there’s no need to distinguish them anymore since they all support the same interface.

public void CreatePost(Post post, ILimit limit)
{
    if(limit.IsLimitReached())
    {
      // do stuff
    }
}