Cannot implement an interface member because it is not public

[Author]

Well, I was trying out this code snippet from

http://msdn.microsoft.com/en-us/library/system.collections.icomparer.aspx

..

using System;
using System.Collecti ons;

public class SamplesArrayLis t {

public class myReverserClass : IComparer {

// Calls CaseInsensitive Comparer.Compar e with the parameters
reversed.
int IComparer.Compa re( Object x, Object y ) {
return( (new CaseInsensitive Comparer()).Com pare( y, x ) );
}

}

public static void Main() {
[snip]
}
}

Why do we have to explicitly qualify the Compare method as below

int IComparer.Compa re( Object x, Object y )

when we implement the Compare method of the IComparer interface?

If I remove qualification, and simply do

int Compare( Object x, Object y )

I get a compile time error which says:

"Cannot implement an interface member because it is not public."

I don't understand this. Please kindly advise. TIA.

[Stanimir Stoyanov]

Re: Cannot implement an interface member because it is not public

Since myReverserClass implements IComparer's methods, they must be with
public accessibility so that outer objects can interact with the interface
members. The following two examples will work:

int IComparer.Compa re( Object x, Object y ) // Default interface
implementation

public int Compare( Object x, Object y ) // Notice the 'public' access
modifer

--
Stanimir Stoyanov

http://stoyanoff.info

"Author" <gnewsgroup@gma il.comwrote in message
news:240fd256-2bb4-4d89-bca9-4c6d9b4c3041@j2 2g2000hsf.googl egroups.com...

Well, I was trying out this code snippet from

http://msdn.microsoft.com/en-us/library/system.collections.icomparer.aspx

.
>
using System;
using System.Collecti ons;
>
public class SamplesArrayLis t {
>
public class myReverserClass : IComparer {
>
// Calls CaseInsensitive Comparer.Compar e with the parameters
reversed.
int IComparer.Compa re( Object x, Object y ) {
return( (new CaseInsensitive Comparer()).Com pare( y, x ) );
}
>
}
>
public static void Main() {
[snip]
}
}
>
Why do we have to explicitly qualify the Compare method as below
>
int IComparer.Compa re( Object x, Object y )
>
when we implement the Compare method of the IComparer interface?
>
If I remove qualification, and simply do
>
int Compare( Object x, Object y )
>
I get a compile time error which says:
>
"Cannot implement an interface member because it is not public."
>
I don't understand this. Please kindly advise. TIA.

[Author]

Re: Cannot implement an interface member because it is not public

On Oct 30, 12:14 pm, "Stanimir Stoyanov"
<stoya...@REMOV ETHIS.live.comw rote:

Since myReverserClass implements IComparer's methods, they must be with
public accessibility so that outer objects can interact with the interface
members. The following two examples will work:
>
int IComparer.Compa re( Object x, Object y ) // Default interface
implementation
>
public int Compare( Object x, Object y ) // Notice the 'public' access
modifer
>
--
Stanimir Stoyanovhttp://stoyanoff.info
>

Yes, that's correct. I didn't notice that the public qualifier is
missing. Maybe the compiler error message can be more friendly like

"By any chance could you try making this Compare method explicitly
public? Simply add "public" to the front and see what happens."

;-)

[Jesse Houwing]

Re: Cannot implement an interface member because it is not public

Hello Author,

Well, I was trying out this code snippet from

http://msdn.microsoft.com/en-us/library/system.collections.icomparer.a

spx .
>
using System;
using System.Collecti ons;
public class SamplesArrayLis t {
>
public class myReverserClass : IComparer {
>
// Calls CaseInsensitive Comparer.Compar e with the parameters
reversed.
int IComparer.Compa re( Object x, Object y ) {
return( (new CaseInsensitive Comparer()).Com pare( y, x ) );
}
}
>
public static void Main() {
[snip]
}
}
Why do we have to explicitly qualify the Compare method as below
>
int IComparer.Compa re( Object x, Object y )
>
when we implement the Compare method of the IComparer interface?
>
If I remove qualification, and simply do
>
int Compare( Object x, Object y )
>
I get a compile time error which says:
>
"Cannot implement an interface member because it is not public."
>
I don't understand this. Please kindly advise. TIA.

When you use IComparer.Copar e, the compiler will egnerate a public method
for you. But if you don't specity the explicit interface name, it will default
to private.

To solve your issue, simply change the signiatyure to public inr Compare
and your problems will go away.

--
Jesse Houwing
jesse.houwing at sogeti.nl