oop - c# OO advice for inherited attribute classes -

i oo correct advice please. correct way of accessing attribute data inherited classes.

assuming 3 classes:

public abstract class vehicle {   public int id {get; set; }       public int wheels {get; set; }   public string name {get; set; }   public string color {get; set; }  }  public class car : vehicle  {  }  public class truck : vehicle  {   public int loadcapacity {get; set; }    } 

my first thought create repository of kind gives me attributes of whatever i'm looking for.

there 2 types of queries see need:

1. return attributes of vehicle specific id
2. give me vehiclesof specific type

so:

public class vehiclerepository {     icollection <???> _vehicles;      ??? getvehicle(int id);     ??? getvehicles(??? vehicletype); } 

the ??? unknowns.

my thought add interface ivehicle , implement vehicle it. result like:

public class vehiclerepository {     icollection <ivehicle> _vehicles;      ivehicle getvehicle(int id);     icollection <ivehicle> getvehicles(ivehicle vehicletype); } 

this doesnt work.

public ivehicle getvehicle(int id) {     return _vehicles.first(x=>x.id == id);     // above want compile interface has no attributes } 

if use vehicle instead of ivehicle, 'first(x=>x.id == id)' work fine not return 'loadcapacity' if vehicle truck.

looking @ getvehicles function, thinking like:

public icollection <t> getvehicles <t> () {     var vehicles = _vehicles.where(???);     return vehicles; } 

a bit lost on should go in there avoid reflection , reading assemblies , class types, etc.

thanks advice.

to store , vericles, need like:

class vehiclerepository {     list<vehicle> vehicles; } 

to retrieve them, use ienumerable<t>.oftype<u>():

vehiclerepository repository = ... repository.vehicles.oftype<car>(); // of cars repository.vehicles.oftype<truck>(); // of trucks 

if wanted fancy though, make vehiclerepository collection own making implement ienumerable<t>. consider:

class vehiclerepository : ienumerable<vehicle> {     list<vehicle> vehicles;      public ienumerator<vehicle> getenumerator() {         return vehicles.getenumerator();     }      system.collections.ienumerator system.collections.ienumerable.getenumerator() {         return this.getenumerator();     } } 

then can query against collection itself, in:

public static void main() {     vehiclerepository repository = ...;      // notice skip accessing vehicles member     // because implementing ienumerable<t> class     // becomes collection. can use oftype<t> directly.     repository.oftype<car>();  } 

edit: getvehiclebyid, might try this:

class vehiclerepository : ienumerable<vehicle> {     list<vehicle> vehicles;      public vehicle getvehiclebyid(int32 id) {         return vehicles[id];     } } 

you use indexer, so:

class vehiclerepository : ienumerable<vehicle> {     list<vehicle> vehicles;      public vehicle this[int32 id] {         { return vehicles[id]; }     } } 

to loadcapacity truck, have this:

public static void main() {    vehiclerepository repository = ...     // assuming index 0 truck    truck truck = (truck)repository.getvehiclebyid(0);    truck.loadcapacity = ... } 

one cheaty way items of particular type (when bound ui, i.e. assuming you're using strings) without using reflection match tostring values of type names. example:

public static void main() {    vehiclerepository repository = ...     // assume we're storing off typename in ui dropdown.    // when user selects it, automatically have correct    // type name want filter by.    string trucktypename = typeof(truck).gettype().tostring();           // filter types matching type name. inefficient,    // avoid reflection.    repository.where(vehicle => vehicle.gettype().tostring() == trucktypename) }