How to force inheriting class's method implementation to call base method before invoke own implantation?

Question

I wrote some not sealed class that contain 3 virtual public method and one private method.

And i make this class public that all my develop group member could use this class ( include inherits and override the virtual public methods ) .

One of the private method name is 'PrivateMethod77()'.

Each time the public method 'PublicMethod77()' is call => the 'PrivateMethod77' is call in the first line of the method implementation ( after this line there are more implication logic ).

I want to keep this logic and 'force' the inherits and override of the method PublicMethod77 to call the PrivateMethod77 method as the first line of the PublicMethod77

Is there a way to do it ?

Answer 1

I don't think that you can enforce the inheriting classes to always first call a method's super implementation, but:

Normally I use a Template method pattern for cases like this:

public abstract class TemplateEnforcer
{
    private void TheSame()
    {
        Console.WriteLine("Everyone calls me;");
    }

    public void TemplateMethod()
    {
        this.TheSame();
        this.NeedsImplementation();
    }

    protected abstract void NeedsImplementation();
}

public class TemplateImplementer : TemplateEnforcer
{
    protected override void NeedsImplementation()
    {
        Console.WriteLine("Implemented in TemplateImplementer");
    }
}

Code output for this call new TemplateImplementer().TemplateMethod():

    //Everyone calls me;
    //Implemented in TemplateImplementer

Template method pattern benefits:

1. Implementation of abstract method is forced.
2. The code is kept DRY.
3. Bugs are avoided and devs are guided in their development.