How to create Items based on a Type

[Lokai]

How to create Items based on a Type

OK, this one is hard even to describe, so I will post some pseudo code to illustrate.

using System;
 
namespace MyWorld
{
   public class BaseShape : Item
   {
      //code here
   }
}

using System;
 
namespace MyWorld
{
   public class BaseSquare : BaseShape
   {
      //code here
   }
}

using System;
 
namespace MyWorld
{
   public class BaseCircle : BaseShape
   {
      //code here
   }
}

using System;
 
namespace MyWorld
{
   public class BaseTriangle : BaseShape
   {
      //code here
   }
}

Now, what I want to do is based on this next bit of code, so its the most important part. Lets pretend that I have many classes that are all Shapes. Some of them are Derived from Square, some from Circle, and some from Triangle. The one below is Derived from Square. I have named it DerivedSquare1 for simplicity. It has 2 variables, both Types, because they can be any type of Shape, one based on Circle, and the other based on Triangle. But I do not know which during Scripting, because there are many, like DerivedTriangle1, DerivedTriangle2, etc. SO HERE IS THE QUESTION: How do I create the items based on a Type? I don't just want to create BaseTriangle and BaseCircle, because they don't have all the code I need, it has to be specific Types which are derived from the base types.

Am I missing something easy?

[/code]

using System;
 
namespace MyWorld
{
   public class DerivedSquare : BaseSquare
   {
      public Type TriangleType;
      public Type CircleType;
      // HERE IS WHERE I WANT TO CREATE SOME ITEMS
      Item i = new Item; //not what I want.... I want somehow to call typeof(TriangleType) or something...??
      Item j = new Item;
   }
}

 

[Khaz]

The .NET Framework provides a method for doing this: Activator.CreateInstance( Type type )
You could implement as such:

using System;

namespace MyWorld
{
	public class DerivedSquare : BaseSquare
	{
		public Type TriangleType = typeof( Triangle );
		public Type CircleType = typeof( Circle );

		TriangleType i = null;

		try{ i = Activator.CreateInstance( TriangleType ) as TriangleType; }
		catch{}

		if( i != null )
			//creation was successful
	}
}

You have to cast the value returned from CreateInstance because it is returned as an Object. It is also a good idea to use the try/catch as this method is not always "safe."

 

[Lokai]

You rock!

Karma++ (or should that be Karma# ?)

 

[Lokai]

One problem.....

TriangeType is not a class, its a variable....

TriangleType is a Type variable. That Type could be DerivedTriangle1, DerivedTriangle2, etc.

I can't use:

TriangeType i = null;

because TriangleType is not a class or Type, its a variable.

And I don't want to use:

DerivedTriange1 i = null;
try{ i = Activator.CreateInstance( typeof( DerivedTriange1 ) ) as DerivedTriange1; }

because I don't know if it's DerivedTriange1 or not.

Help!

 

[Khaz]

Use object instead, then:

object i = null;

try{ i = Activator.CreateInstance( TriangleType ); }
catch{}

if( i != null ) {
	//creation successful, start checking via reflection...
	if( i is DerivedTriangle1 ) {
		//yay
	} else if( i is DerivedTriangle2 ) {
		//yay #2
	}
}

 

[Lokai]

Thank you again.

Now, lets move this into RunUO terms, if you don't mind. An example a little closer to home...(this is not my real code, but simulates the concept.)

Tell me if this code would work for what I am trying to do:

public class CreateMobile
{
            public Type MobileType { get{ return m_MobileType; } set{ m_MobileType = value; } }
 
            public void DoCreate( Mobile from )
            {
                        Mobile m = null;
                        try { m = Activator.CreateInstance( MobileType ); }
                        catch{}
                        if( m != null ) //creation was successful
                        {
                                    if ( m is from.Combatant ) //If we are fighting the same type of Monster...
                                                from.SendGump( new SuccessGump( from, m ) );
                        }
            }
}

 

[Khaz]

Close. Highlighted recommended changes:

public class CreateMobile
{
            public Type MobileType { get{ return m_MobileType; } set{ m_MobileType = value; } }
 
            public void DoCreate( Mobile from )
            {
                        Mobile m = null;
                        try { m = Activator.CreateInstance( MobileType ) [highlight]as Mobile[/highlight]; }
                        catch{}
                        if( m != null ) //creation was successful
                        {
                                    if ( [highlight]m.Combatant != null &&[/highlight] m is from.Combatant[highlight].GetType()[/highlight] ) //If we are fighting the same type of Monster...
                                                from.SendGump( new SuccessGump( from, m ) );
                        }
            }
}

 

[Jeff]

You are looking at this all wrong, or I am not understanding, But it seems to me you want to do something like this instead.

	public class DerivedSquare : BaseSquare
	{
		public BaseShape TriangleType;
		public BaseShape CircleType;
	
		public DerivedSquare()
		{
			//You can make TriangleType anything you want since all shapes derive from the same BaseShape
			TiangleType = new BaseTriangle();
			//Or even this if you REALLY wanted to
			TiangleType = new BaseCircle();
		}

Make sense?