explicit interface implementation

If a class C implements two interfaces, if1 and if2, each of which have a property w with the same signature, then C.w is considered to implement both if1.w and if2.w as the following example makes clear:

using System;

interface if1

{

int w {get; set;}

}

interface if2

{

int w {get; set;}

}

class C : if1, if2

{

public int w {get; set;}

}

class Test

{

static void Main()

{

C c = new C();

if1 I = c;

I.w = 3;

Console.WriteLine(c.w); // 3

if2 J = c;

J.w = 4;

Console.WriteLine(c.w); // 4

Console.ReadKey();

}

}

Even though we've set w using interface references, we can still access it in both cases through a C reference.

However, if you want each interface to have separate implementations of w within C, then you need to use explicit interface implementation. Each implementation of w can then only be accessed via an interface reference of the appropriate type, as the following revised example shows:

using System;

interface if1

{

int w {get; set;}

}

interface if2

{

int w {get; set;}

}

class C : if1, if2

{

int if1.w {get; set;}

int if2.w {get; set;}

}

class Test

{

static void Main()

{

C c = new C();

if1 I = c;

I.w = 3;

Console.WriteLine(I.w); // 3

if2 J = c;

J.w = 4;

Console.WriteLine(J.w); // 4

Console.ReadKey();

}

If you tried to use c.W, instead of I.w or J.w, then you'd get a compiler error.

2 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
If a class C implements two interfaces, if1 and if2, each of which have a property w with the same signature, then C.w is considered to implement both if1.w and if2.w as the following example makes clear:

using System;

interface if1
{
int w {get; set;}
}

interface if2
{
int w {get; set;}
}

class C : if1, if2
{
public int w {get; set;}
}

class Test
{
static void Main()
{
C c = new C();
if1 I = c;
I.w = 3;
Console.WriteLine(c.w); // 3
if2 J = c;
J.w = 4;
Console.WriteLine(c.w); // 4
Console.ReadKey();
}
}

Even though we've set w using interface references, we can still access it in both cases through a C reference.

However, if you want each interface to have separate implementations of w within C, then you need to use explicit interface implementation. Each implementation of w can then only be accessed via an interface reference of the appropriate type, as the following revised example shows:

using System;

interface if1
{
int w {get; set;}
}

interface if2
{
int w {get; set;}
}

class C : if1, if2
{
int if1.w {get; set;}
int if2.w {get; set;}
}

class Test
{
static void Main()
{
C c = new C();
if1 I = c;
I.w = 3;
Console.WriteLine(I.w); // 3
if2 J = c;
J.w = 4;
Console.WriteLine(J.w); // 4
Console.ReadKey();
}
}

If you tried to use c.W, instead of I.w or J.w, then you'd get a compiler error.
nishant kumar14y ago
thanks for the help vulpes.