Question

I have designed a hierarchy, every class has 2 readonly properties mapped to 2 private fields.

Every class has a cosntructor that inherits the parent class one.

The problem is that at every level of hierarchy the number of parameters increase of 2:

TBaseClass.Create (par1, par2);
TSubClass.Create(par1, par2, par3, par4);
TSubSubClass.Create(par1, par2, par3, par4, par5, par6);
[...]

Is it ok to have constructors with 6-8 parameteres? After creation my objects should be immutable, so this is why I try to initialize all fileds in the constructors.

Is there another technique you can suggest or should I go with the above mentioned approach? Thanks.

Answer 1

As long as they’re well-documented, I’ve never had any stigma against functions with large numbers of parameters. So an 8-param constructor wouldn’t scare me.

However, I can see where the explosion-of-params could occur here, especially if you start adding more than 2 properties per object. I could also see an uncomfortable proliferation of constructor overloads, if some of those params can be defaulted/optional.

With that in mind, you might want to encapsulate the complexities of setting all those params, by using a construction pattern. Builder comes to mind, though Factory or Prototype might also be useful.