Disposing Custom Class : Setting NULL VS .Dispose

Question

Possible Duplicate:
Calling null on a class vs Dispose()

Just want some information regarding Disposing an Object.

I have create a Employee Class which i inherit from IDISPOSIBLE Interface. Below is the sample Code

public class Employee : IDisposable 
 {
      private Int32 _RunID;

      public Int32 RunID { get { return _RunID; } set { _RunID = value; } }

        public void Dispose()
        {
            //Dispose(true);
        }
 }

Now my Question is, it a Good Coding Practice to Dispose every class we create and implementing/Inheriting it with IDisposible Interface even i have seen many other people code they directly set ObjEmployee = null; so just got confused which is good setting NULL or Implementing it With IDisposible Interface or None Of the Above ?

http://stackoverflow.com/questions/574019/calling-null-on-a-class-vs-dispose ... http://stackoverflow.com/questions/584549/whats-the-point-of-overriding-disposebool-disposing-in-net ... http://stackoverflow.com/questions/12368/how-to-dispose-a-class-in-net ... — Tim Schmelter, Sep 27 '11 at 07:19
@Tim Schmelter - are you suggesting that this may, perhaps, be duplicative? — Damien_The_Unbeliever, Sep 27 '11 at 07:31
@Damien: Yes, but first of all i wanted to give Rick something to read. — Tim Schmelter, Sep 27 '11 at 07:37
This is a duplicate. Just check [this question](http://stackoverflow.com/questions/574019/calling-null-on-a-class-vs-dispose) with [this amazing answer](http://stackoverflow.com/questions/574019/calling-null-on-a-class-vs-dispose/574659#574659) by [John Skeet](http://stackoverflow.com/users/22656/jon-skeet). — Marc, Sep 27 '11 at 07:34

score 6 · Accepted Answer · answered Sep 27 '11 at 07:20

6

It depends, do you have managed resources (File handles, sockets, connections, etc....) that need to be gotten rid of along with your object? If yes then you need a Dispose() if your class contains basic types or just information you do not need to dispose and setting to null will give a hint to the GC to clear that memory.

answered Sep 27 '11 at 07:20

Jesus Ramos

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And setting it to null only matters if the your looking at variables that won't go out of scope. Variables that go out of scope, any objects assigned to them that no longer exist in any scope will eventually be picked up by the GC, so setting these variables to null would be pointless and just litter your code. – Sekhat Mar 20 '13 at 11:41

score 3 · Answer 2 · answered Sep 27 '11 at 07:32

3

When you set ObjEmployee = null, you only mark the object instance to be ready for the Garbage Collector, but you have no influence over when the actual clean-up would take place, and it may take a while. When you use the Dispose() method, the GC runs immediately and frees the memory the object was using.

answered Sep 27 '11 at 07:32

Maja Remic

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Calling Dispose() does not trigger the GC. – Bryan Crosby Mar 20 '12 at 19:45

score 2 · Answer 3 · answered Sep 27 '11 at 14:50

The fundamental question, in deciding whether a class should implement IDisposable, is whether instances of that class have taken on the responsibility of seeing that other entities get cleaned up; typically those other entities will be altering their behavior on behalf of the IDisposable object and at the expense of other entities, and the IDisposable object is responsible for letting them know when they no longer need to do so.

For example, if any code, anywhere, uses the C function fopen() to open for read-write access a file which is located on a server, the server will alter its behavior by forbidding anyone else from accessing the file until it receives word that the program that opened it has no more need of it. When the program no longer needs exclusive use of the file, it can call fclose() which will in turn cause the server to be notified that the file should again be available to other applications.

If a method in a C# class calls a routine which calls fopen(), and that routine returns after putting the FILE* in a place the C# program knows about but nothing else does, that method takes on a responsibility for seeing that fclose() must somehow get called with that FILE*. The file needs to be fclosed(), and nothing else in the system has the information or impetus necessary to do so, so the responsiblity falls to that C# class.

If the C# method were to return without storing the FILE* anywhere, the file would never get closed, and nobody else, anywhere in the universe, would be able to use it unless or until the application exits. If the C# method has to exit without yielding exclusive use of the file, it must store the FILE* in a way that will ensure that someone, somewhere, will clean it up after exclusive use is no longer required. The normal pattern would be for the method to store the FILE* in a class field, and for class containing the method to implement IDisposable by copying and blanking that field, seeing if it was non-blank, and if it was non-blank, calling fclose() the stored FILE*.

The important thing to realize is that when an object is destroyed by the garbage collector, the system won't care what's in any of the object fields. It won't even look at them. What matters is whether the object has any unfulfilled responsibilities for ensuring that outside entities, which may not even be on the same machine, are informed when their services are no longer needed.

Disposing Custom Class : Setting NULL VS .Dispose

3 Answers3