Question

Given web service method:

public void FindSomeEntities(int? Id, string param1, int? param2, ...)

Refactored:

public void FindSomeEntities(SelectionParameters selectionParameters)

class SelectionParameters
{
    public int? Id;
    public string param1;
    public int? param2
    ...
}

Pros:

1. too many parameters in original web service method reduced to the
   only one
2. if there is need to change we won’t have to change the
   interface of the method – only the definition of SelectionParameters

Cons:

1. class SelectionParameters hasn’t any business value – it’s used only
   as helper class and it’s used in a single method. As a result we’ll
   have many methods with 1 parameters and plenty of one-off classes
2. Actually the interface IS changed, we just push these changes a bit
   deeper.

Answer 1

This refactoring is called Introduce Parameter Object. It is likely to be a good idea if the parameters are naturally related to each other, and especially if they’re frequently used together as parameter lists to multiple methods.