I have class A which define class B:
B b=new B()
I would like to call to a function in class A from B.when I tried to make this function- static- i got an error cause i have in that function-
Dispatcher.BeginInvoke...
Is there another way to do it?
Why not just pass a reference of A to B.
Something like
public class A
{
public A()
{
B b = new B(this);
}
}
public class B
{
public B(A a)
{
}
}
Or you could make it a property of B.
Something like
public class A
{
public A()
{
B b = new B
{
MyA = this
};
}
}
public class B
{
public A MyA;
}
Related
(I really struggled with coming up with a good title for this question, if anyone wants to help out with that..)
So I'm having an issue designing something. Essentially I have a class A, which is composed of an array of objects of type B. I only want the interface of class A to be exposed, and want to keep class B essentially hidden to any user. I want to be able to perform operations on type B and its data, but only through class A's interface/methods calling methods of an instance of B. The part where it gets tricky is that I want to create a method that performs operations on members of type B, but I wanted to implement an interface and then have a class that implements that interface because I want my user to be able to create their own implementation of this method. I was thinking of doing somtehing like:
public class A
{
B[] arr;
C c;
public A(C c)
{
arr = new B[100];
this.c = c;
}
public void method1()
{
var b = new B();
b.someMethodofb(c); // pass c to the method of b
}
private class B
{
someMethodOfb(C c)
{
}
}
}
public class C : Interface1
{
public void method(B b)
{
//interface method we have implemented
}
}
I made the class B private because I only want class A to be publicly available so anything that happens to class B happens through class A, which is also why I nested B within A. But since class B is private, will I be able to use it as a parameter for the method of my class C? The method of Interface1 implemented is going to affect the internal implementation of how B performs someMethodOfb, which is why I think I need to pass it in to be able to maintain the hidden nature of class B. Could there be a better way for me to design this and be able to achieve the goals I set out in the first paragraph?
I would suggest you add another interface for the public known side of B, have B implement that interface and have C's method(s) use the interface.
public interface IC {
void method(IB b);
}
public interface IB {
int Priority { get; set; }
int Urgency { get; set; }
}
public class A {
B[] arr;
IC c;
public A(C c) {
arr = new B[100];
this.c = c;
}
public void method1() {
var r = (new Random()).Next(100);
arr[r].someMethodOfB(c); // pass c to the method of b
}
private class B : IB {
public int Priority { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
public int Urgency { get => throw new NotImplementedException(); set => throw new NotImplementedException(); }
internal void someMethodOfB(IC aC) {
aC.method(this);
throw new NotImplementedException();
}
}
}
public class C : IC { // user implements
public void method(IB b) {
if (b.Priority > 10 || b.Urgency > 10)
; // do something with BI using b
throw new NotImplementedException();
}
}
Now the user of the classes needs to know IC so they can create C and they need to know IB so they can write the body of the methods in C, but they don't need to know all of B or have access to B.
Let's use concrete examples :)
Say, we have three classes: Customer, Order, and OrderProcessor. Customer and Order are entities representing a customer and an order respectively, while OrderProcessor will process an order:
public interface IOrderProcessor
{
void ProcessOrder(IOrder order);
}
public interface IOrder
{
void FinalizeSelf(IOrderProcessor oProc);
int CustomerId {get; set;}
}
public class Customer
{
List<IOrder> _orders;
IOrderProcessor _oProc;
int _id;
public Customer(IOrderProcessor oProc, int CustId)
{
_oProc = oProc;
_orders = new List<IOrder>();
_id = CustId;
}
public void CreateNewOrder()
{
IOrder _order = new Order() { CustomerId = _id };
_order.FinalizeSelf(_oProc);
_orders.Add(_order);
}
private class Order : IOrder
{
public int CustomerId {get; set;}
public void FinalizeSelf(IOrderProcessor oProcessor)
{
oProcessor.ProcessOrder(this);
}
}
}
public class ConcreteProcessor : IOrderProcessor
{
public void ProcessOrder(IOrder order)
{
//Do something
}
}
I don't know how to define my question (probably already asked but didn't found it).
I want to create a constructor for a class B inherited from A taking a B object as parameter used to be a copy of it.
There can be something like this :
class B : A
{
public String NewField;
public B(A baseItem, String value)
{
// Create new B to be a copy of baseItem
???; // something like : this = baseItem
// Add new field
NewField = value;
}
}
Objective is to create an object B which is the exact copy of an A object with on filed more.
Use the base keyword to call the parent class constructor, giving your parent class instance as a parameter. Then create a copy constructor in your parent, and you're done.
class A
{
public A(A a)
{
// Copy your A class elements here
}
}
class B : A
{
public String NewField;
public B(A baseItem, String value)
: base(baseItem)
{
NewField = value;
}
}
You could implement a CopyProperties method, which will copy the properties values.
using System;
public class A
{
public string Filename {get; set;}
public virtual void CopyProperties(object copy)
{
((A)copy).Filename = this.Filename;
}
}
public class B : A
{
public int Number {get;set;}
public override void CopyProperties(object copy)
{
base.CopyProperties(copy);
((B)copy).Number = this.Number;
}
}
public class Program
{
public static void Main()
{
B b = new B { Filename = "readme.txt", Number = 42 };
B copy = new B();
b.CopyProperties(copy);
Console.WriteLine(copy.Filename);
Console.WriteLine(copy.Number);
}
}
Just a basic programming question.
public class ClassA
{
int i = 10;
void Start()
{
ClassB b = new ClassB(this);
b.DoSomething();
}
}
public class ClassB
{
ClassA a;
public ClassB(ClassA a)
{
this.a = a;
}
void DoSomething()
{
Console.WriteLine(a.i);
}
}
I would really like to omit the a:
Console.WriteLine(a.i);
->
Console.WriteLine(i);
What is the most reasonable method of achieving this?
(Note: ClassB must not inherit from ClassA, as ClassA inherits from something ClassB cannot. And I suppose I should say I don't want to pass parameters to the functions, so DoSomething(i) is not applicable.)
You can create a property. Please note that a.i still needs to be public for both your example and mine.
public class ClassB
{
private ClassA a;
public ClassB(ClassA a)
{
this.a = a;
}
public int i { get { return a.i; } }
void DoSomething()
{
Console.WriteLine(i);
}
}
and sorry in advance if this question has been solved previously.
I am creating a small library in C# and am hoping to have class A be able to modify the data members of class B, where class A and B exist in the same namespace, C.D. This is not a problem to accomplish though I would like class E, in namespace C, to not be able to access the data members of B.
namespace C.D
{
class B
{
modifier int
a,
b;
public B()
{
}
}
class A
{
public A() {}
public B DoStuff()
{
B b = new B();
b.a = 1; b.b = 2;
return b;
}
}
}
namespace C
{
class E
{
static void Main(String[] args)
{
A a = new A();
B b = a.DoStuff();
}
}
}
In my main method above I would like every class in the namespace C.D to be able to alter the data members of a class B object though nothing outside of the C.D namespace to be able to modify class B object data members.
Is there any way to do this by changing the namespace structure, modifiers, or implementing specific design patterns?
Thank you all in advance. : )
You can use the "internal" access modifier if you're willing to move the relevant classes in C.D to a separate assembly.
namespace C.D
{
class B
{
internal int a;
internal int b;
public B()
{
}
}
}
One way to achieve this is by:
Moving Class A's definition into Class B (nesting it within class B { ... })
Making Class B's fields (a and b) private.
i.e.
namespace C.D
{
class B
{
private int a, b;
public B()
{
}
class A
{
public A() { }
public B DoStuff()
{
B b = new B();
b.a = 1; b.b = 2;
return b;
}
}
}
}
namespace C
{
class E
{
static void Main(String[] args)
{
A a = new A();
B b = a.DoStuff();
}
}
}
Another way to achieve this is to make Class B's fields protected, then make all classes that should have access to Class B's fields derive from Class B. This way you won't need to nest Class A inside Class B. i.e.
namespace C.D
{
class B
{
protected int a, b;
public B()
{
}
}
class A : B
{
public A() {}
public B DoStuff()
{
B b = new B();
b.a = 1; b.b = 2;
return b;
}
}
}
namespace C
{
class E
{
static void Main(String[] args)
{
A a = new A();
B b = a.DoStuff();
}
}
}
Is it necessary to emit OpCode.CastClass(typeof(A)) when you having a reference to instance of (B) on top of stack, where B is class, derived from A, when preparing for a call to method with argument of type A?
Addition:
interface IFoo
{
void IFoo();
}
public class A:IFoo
{
public void IFoo()
{
}
}
public class B:A,IFoo
{
new public void IFoo()
{
}
}
var b = new B();
(b as IFoo).Foo();
((b as A) as IFoo).Foo();
I guess you have something like this:
class A
{
public void Foo() { }
}
class B : A
{
}
and need to decide between:
B b = new B();
b.Foo();
and
B b = new B();
((A)b).Foo();
Both work. But the cast is not necessary, because B inherits all members from A.