Call parent method from child class c

Question

This is a slightly different question from previous answers I have seen or I am not getting it  I have a parent class with a method named MyMethod   and a variable public Int32 CurrentRow   public void MyMethod              this UpdateProgressBar            In the parent I create a new instance of ChildClass  Boolean loadData   true  if  loadData              ChildClass childClass   new ChildClass             childClass LoadData this Datatable           In the child Class LoadData   method I want to be able to set the CurrentRow variable of the parent and call the MyMethod   function   How do I do this

User · Answer

One way to do this would be to pass the instance of ParentClass to the ChildClass on construction

public ChildClass
{
    private ParentClass parent;

    public ChildClass(ParentClass parent)
    {
        this.parent = parent;
    }

    public void LoadData(DateTable dt)
    {
       // do something
       parent.CurrentRow++; // or whatever.
       parent.UpdateProgressBar(); // Call the method
    }
}

Make sure to pass the reference to this when constructing ChildClass inside parent:

if(loadData){

     ChildClass childClass = new ChildClass(this); // here

     childClass.LoadData(this.Datatable);

}

Caveat: This is probably not the best way to organise your classes, but it directly answers your question.

EDIT: In the comments you mention that more than 1 parent class wants to use ChildClass. This is possible with the introduction of an interface, eg:

public interface IParentClass
{
    void UpdateProgressBar();
    int CurrentRow{get; set;}
}

Now, make sure to implement that interface on both (all?) Parent Classes and change child class to this:

public ChildClass
{
    private IParentClass parent;

    public ChildClass(IParentClass parent)
    {
        this.parent = parent;
    }

    public void LoadData(DateTable dt)
    {
       // do something
       parent.CurrentRow++; // or whatever.
       parent.UpdateProgressBar(); // Call the method
    }
}

Now anything that implements IParentClass can construct an instance of ChildClass and pass this to its constructor.

User · Answer

Found the solution   In the parent I declare a new instance of the ChildClass   then bind the event handler in that class to the local method in the parent  In the child class I add a public event handler   public EventHandler UpdateProgress    In the parent I create a new instance of this child class then bind the local parent event to the public eventhandler in the child  ChildClass child   new ChildClass    child UpdateProgress    this MyMethod  child LoadData this MyDataTable     Then in the LoadData   of the child class I can call  private LoadData         this OnMyMethod        Where OnMyMethod is   public void OnMyMethod             has the event handler been assigned       if  this UpdateProgress   null                     raise the event          this UpdateProgress this  new EventArgs                This runs the event in the parent class

User · Answer

To follow up on the comment by suhendri to Rory McCrossan answer   Here is an Action delegate example   In child add   public Action UpdateProgress      In place of event handler declaration                                   declare an Action delegate       private LoadData         this UpdateProgress          call to Action delegate - MyMethod in                                  parent     In parent add      The 3 lines in the parent becomes  ChildClass child   new ChildClass    child UpdateProgress   this MyMethod      assigns MyMethod to child delegate

User · Answer

To access properties and methods of a parent class use the base keyword  So in your child class LoadData   method you would do this   public class Child   Parent        public void LoadData                  base MyMethod       call method of parent class         base CurrentRow   1     set property of parent class            other stuff              Note that you would also have to change the access modifier of your parent MyMethod   to at least protected for the child class to access it

[c#] Call parent method from child class c#

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