How to delete object

Question

I need to create a method of class that delete the instance   public class Car       private string m Color       public string Color               get   return m Color            set   m Color   value               public Car                    public void Delete                   This method will delete the instance          so any references to this instance will be now null            class Program       static void Main  string   args                 Car car   new Car             car Delete             if car  null              Console WriteLine  It works             else             Console WriteLine  It doesn t work              I want to know if there is any possible solution  even if it is not recommended  how to do this   Instance of this class will be stored in hundreds of different class  I will try to describe this  for example there will be these classes   public class CarKey       private Car m Car       public Car Car               get   return m Car               public bool CarExist  get  return m Car    null           public CarKey  Car car                 m Car   car           public class Garages        private List lt Car gt  m Collection   new List lt Car gt           private int m Size        public int Size  get  return m Size            public Garages  int size                   for int i 0 i lt size i                 m Collection Add null                public bool IsEmpty  int garage                   return m Collection garage     null               public void InsertCar  Car car  int garage                    if  m Collection garage     null               throw new Exception  This garage is full                m Collection garage    car                public Car GetCar  int garage                   if  m Collection garage     null              throw new Exception  There is no car  maybe it was deleted               return m Collection garage

User · Answer

From any class you can t set its value to null  This is not allowed and doesn t make sense also - public void Delete         this   null   lt -- NOT ALLOWED    You need an instance of class to call Delete   method so why not set that instance to null itself once you are done with it  Car car   new Car       Use car objects and once done set back to null car   null    Anyhow what you are trying to achieve is not possible in C   I suspect from your question that you want this because there are memory leaks present in your current design which doesn t let the Car instance to go away  I would suggest you better profile your application and identify the areas which is stopping GC to collect car instance and work on improving that area

User · Answer

FLCL s idea is very correct  I show you in a code      public class O1 lt T gt  where T  class               public Guid Id   get            public O1 Guid id                        Id   id                    public bool IsNull   gt   GlobalHolder Holder ContainsKey Id           public T Val   gt  GlobalHolder Holder ContainsKey Id     T GlobalHolder Holder Id    null            public class GlobalHolder               public static readonly Dictionary lt Guid  object gt  Holder   new Dictionary lt Guid  object gt             public static O1 lt T gt  Instantiate lt T gt    where T  class  new                         var a   new T                var nguid   Guid NewGuid                var b   new O1 lt T gt  nguid               Holder nguid    a              return b                    public static void Destroy lt T gt  O1 lt T gt  obj  where T  class                       Holder Remove obj Id                        public class Animal                   public class AnimalTest               public static void Test                         var tom   GlobalHolder Instantiate lt Animal gt                 var duplicateTomReference   tom              GlobalHolder Destroy tom               Console WriteLine   quot  duplicateTomReference IsNull  quot                   prints true                  Note  In this code sample  my naming convention comes from Unity

User · Answer

You cannot delete an managed object in C    That s why is called MANAGED language  So you don t have to troble yourself with delete  just like in c      It is true that you can set it s instance to null  But that is not going to help you that much because you have no control of your GC  Garbage collector  to delete some objects apart from Collect  And this is not what you want because this will delete all your collection from a generation   So how is it done then    So   GC searches periodically objects that are not used anymore and it deletes the object with an internal mechanism that should not concern you   When you set an instance to null you just notify that your object has no referene anymore ant that could help CG to collect it faster

User · Answer

Use a collection that is a static property of your Car class  Every time you create a new instance of a Car  store the reference in this collection   To destroy all Cars  just set all items to null

User · Answer

I would suggest   to use  Net s IDisposable interface if your are thinking of to release instance after its usage   See a sample implementation below   public class Car   IDisposable       public void Dispose                Dispose true             any other managed resource cleanups you can do here        Gc SuppressFinalize this            Car           finalizer              Dispose false            protected virtual void Dispose bool disposing            if    disposed               if  disposing                  if   stream    null   stream Dispose       say you have to dispose a stream                 stream   null       disposed   true                  Now in your code   void main        using var car   new Car                 do something with car         here dispose will automtically get called

User · Answer

What you re asking is not possible  There is no mechanism in  Net that would set all references to some object to null   And I think that the fact that you re trying to do this indicates some sort of design problem  You should probably think about the underlying problem and solve it in another way  the other answers here suggest some options

User · Answer

It sounds like you need to create a wrapper around an instance you can invalidate   public class Ref lt T gt  where T   class       private T instance      public Ref T instance                this instance   instance             public static implicit operator Ref lt T gt  T inner                return new Ref lt T gt  inner              public void Delete                 this instance   null             public T Instance               get   return this instance              and you can use it like   Ref lt Car gt  carRef   new Car    carRef Delete    var car   carRef Instance        car is null   Be aware however that if any code saves the inner value in a variable  this will not be invalidated by calling Delete

User · Answer

You can proxyfy references to your object with  for example  dictionary singleton  You may store not object  but its ID or hash and access it trought the dictionary  Then when you need to remove the object you set value for its key to null

User · Answer

You can use extension methods to achive this   public static ObjRemoverExtension       public static void DeleteObj lt T gt  this T obj  where T  new                 obj   null            And then you just import it in a desired source file and use on any object  GC will collect it  Like this Car DeleteObj    EDIT Sorry didn t notice the method of class all references part  but i ll leave it anyway

[c#] How to delete object?

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