Philosophy Object/Properties Parameter Query

I'm looking at some code I've written and thinking "should I be passing that object into the method or just some of its properties?".

Let me explain:

This object has about 15 properties - user inputs. I then have about 10 methods that use upto 5 of these inputs. Now, the interface looks a lot cleaner, if each method has 1 parameter - the "user inputs object". But each method does not need all of these properties. I could just pass the properties that each method needs.

The fact I'm asking this question indicates I accept I may be doing things wrong.

Discuss......:)

EDIT: To add calrity:

From a web page a user enters details about their house and garden. Number of doors, number of rooms and other properties of this nature (15 in total).

These details are stored on a "HouseDetails" object as simple integer properties.

An instance of "HouseDetails" is passed into "HouseRequirementsCalculator". This class has 10 private methods like "calculate area of carpet", "caclulateExtensionPotential" etc.

For an example of my query, let's use "CalculateAreaOfCarpet" method.

• should I pass the "HouseDetails" object

• or should I pass "HouseDetails.MainRoomArea, HouseDetails.KitchenArea, HouseDetails.BathroomArea" etc

Based on my answer above and related to your edit:

a) You should pass the "HouseDetails" object

Other thoughts:

Thinking more about your question and especially the added detail i'm left wondering why you would not just include those calculation methods as part of your HouseDetails object. After all, they are calculations that are specific to that object only. Why create an interface and another class to manage the calculations separately?

Older text:

Each method should and will know what part of the passed-in object it needs to reference to get its job done. You don't/shouldn't need to enforce this knowledge by creating fine-grained overloads in your interface. The passed-in object is your model and your contract.

Also, imagine how much code will be affected if you add and remove a property from this object. Keep it simple.

Passing individual properties - and different in each case - seems pretty messy. I'd rather pass whole objects.

Mind that you gave not enough insight into your situation. Perhaps try to describe the actual usage of this things? What is this object with 15 properties?, are those "10 methods that use upto 5 of these input" on the same object, or some other one?

After the question been edited

I should definitely go with passing the whole object and do the necessary calculations in the Calculator class.

On the other hand you may find Domain Driven Design an attractive alternative (http://en.wikipedia.org/wiki/Domain-driven_design). With regard to that principles you could add methods from calculator to the HouseDetails class. Domain Driven Design is quite nice style of writing apps, just depends how clean this way is for you.