Difference between revisions of "Composition - 2017"

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Composition is where if you delete the main class the subclasses are deleted along with it, or they no longer work.
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Composition is where objects created within another object are destroyed along with the containing object.
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<syntaxhighlight lang="csharp">
 
<syntaxhighlight lang="csharp">
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   class Location
 
   class Location
 
   {
 
   {
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     }
 
     }
 
   }
 
   }
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</syntaxhighlight>
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As you can see Location is creates an instance of Fox & Warren. So if you remove the instance of location then the Fox & Warren instances for that location will also be destroyed.
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==Other Examples==
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Warrens & Rabbits - warren creates and destroys rabbits:
  
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  class Simulation
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<syntaxhighlight lang="csharp">
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class Warren
 
   {
 
   {
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     private Location[,] Landscape;
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     private const int MaxRabbitsInWarren = 99;
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    private int TimePeriod = 0;
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     private Rabbit[] Rabbits;
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     private int WarrenCount = 0;
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     private int RabbitCount = 0;
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     private int FoxCount = 0;
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</syntaxhighlight>
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    private bool ShowDetail = false;
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    private int LandscapeSize;
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The Warren class declares an array of Rabbit. The constructor method for Warren creates each rabbit:
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    private int Variability;
 
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    private static Random Rnd = new Random();
 
  
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<syntaxhighlight lang="csharp">
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public Warren(int Variability)
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    {
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      this.Variability = Variability;
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      Rabbits = new Rabbit[MaxRabbitsInWarren];
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      RabbitCount = (int)(CalculateRandomValue((int)(MaxRabbitsInWarren / 4), this.Variability));
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      for (int r = 0; r < RabbitCount; r++)
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      {
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        Rabbits[r] = new Rabbit(Variability);
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      }
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    }
 
</syntaxhighlight>
 
</syntaxhighlight>
  
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As you can see Location is part of Simulation, so if you remove the class of Location, Simulation would not work as Location forms a variable within the class that is frequently used.
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So if a Warren is destroyed it will destroy all of the rabbits in that warren also.
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==Other Examples==
 
  
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Warrens & Rabbits - warren creates and destroys rabbits
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=Conclusion=
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Foxes & Warrens - both are ultimately created and destroyed by the simulation
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The following are therefore examples of composition (Composition shown with Filled Diamond):
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*Location to Fox
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*Location to Warren
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*Warren to Rabbit
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*Simulation to Location

Latest revision as of 12:48, 28 May 2017

Composition is where objects created within another object are destroyed along with the containing object. 

  class Location
  {
    public Fox Fox;
    public Warren Warren;

    public Location()
    {
      Fox = null;
      Warren = null;
    }
  }

As you can see Location is creates an instance of Fox & Warren. So if you remove the instance of location then the Fox & Warren instances for that location will also be destroyed.

Other Examples

Warrens & Rabbits - warren creates and destroys rabbits: 

class Warren
  {
    private const int MaxRabbitsInWarren = 99;
    private Rabbit[] Rabbits;
    private int RabbitCount = 0;

The Warren class declares an array of Rabbit. The constructor method for Warren creates each rabbit: 

public Warren(int Variability)
    {
      this.Variability = Variability;
      Rabbits = new Rabbit[MaxRabbitsInWarren];
      RabbitCount = (int)(CalculateRandomValue((int)(MaxRabbitsInWarren / 4), this.Variability));
      for (int r = 0; r < RabbitCount; r++)
      {
        Rabbits[r] = new Rabbit(Variability);
      }
    }

So if a Warren is destroyed it will destroy all of the rabbits in that warren also.

Conclusion

The following are therefore examples of composition (Composition shown with Filled Diamond):

  • Location to Fox
  • Location to Warren
  • Warren to Rabbit
  • Simulation to Location
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