How to deal with class composition when components cannot be accessed from the outside?
- by Chathuranga
For example if I say I have three classes A, B, and C where B and C have a composition relation ship with A. That means the life of B and C is handled by A, and also B and C cannot access directly from the outside.
For some reason my DataService class needs to return objects of B and C as It cant return a object of A as B and C cannot be initialized at the same time. (to be able to initializeC you have to initializeB first).
So that I'm returning DataTables from DataService and then inside the class A those data tables are converted to B / C objects.
If B and C objects cannot be initialized at the same time is it valid to say that B and C have a composition relationship with A?
If its composition is it must to generate A with B and C inside?
What is the proper way to handle this sort of a problem?
EDIT:
Following code explains the way I'm doing it now with DataTables.
Example:
class A
{
private List<B> B;
private List <C> C;
public A()
{
B= new List<B>();
C= new List<C>();
}
public List<B> GetB( DataTable dt)
{
// Create a B list from dt
return B;
}
}
class Presenter
{
private void Show B()
{
_View.DataGrid = A.GetB(DataService.GetAListOfB());
}
}
The actual scenario is I have a class called WageInfo and classes Earning and Deduction having a composition relationship in the design. But for you to generate Deductions first you should Generate earnings and should be saved in a table. Then only you can generate deductions for the earnings to calculate balance wages.
Also note that these contained classes have a one to many relationship with the containing class WageInfo. So actually WageInfo has a List<Earnings> and List<Deduction>
My initial question was, is it ok if my DataService class returns Deductions / Earnings objects (actually lists) not a WageInfo?
Still not clear?
