Implementing generic IEnumerable

  • Thread starter Thread starter Guest
  • Start date Start date
G

Guest

I can't seem to figure this one out... I've searched MSDN and Goog, and made
my best guesses to no avail,, so help would be much appreciated!

public ref class T sealed
: public System::Collections::IEnumerable
, public System::Collections::Generic::IEnumerable<int>
{
// How to implement GetEnumerator() for both interfaces?
// Compiler complains that functions differ only in return type
// which I understand, but can't get the right syntax for explicit
// interface implementations...
};

Explicit interface implementations in .NET SDK show the following syntax:

private: virtual System::Collections::IEnumerator^
System.Collections.IEnumerable.GetEnumerator() sealed =
System::Collections::IEnumerable::GetEnumerator
{ /*function body*/ }

Note the 'dot' scope operator in specifying the method name - it causes a
syntax error when I compile. Changing it to :: the compiler says that's old
syntax. Removing it compiles fine if I don't try to implement the generic
IEnumerable too. Stumped! ;)

Thanks, KH
 
KH,

I can't seem to figure this one out... I've searched MSDN and Goog, and
made
my best guesses to no avail,, so help would be much appreciated!

public ref class T sealed
: public System::Collections::IEnumerable
, public System::Collections::Generic::IEnumerable<int>
{
// How to implement GetEnumerator() for both interfaces?
// Compiler complains that functions differ only in return type
// which I understand, but can't get the right syntax for explicit
// interface implementations...
};

Explicit interface implementations in .NET SDK show the following syntax:

private: virtual System::Collections::IEnumerator^
System.Collections.IEnumerable.GetEnumerator() sealed =
System::Collections::IEnumerable::GetEnumerator
{ /*function body*/ }

Note the 'dot' scope operator in specifying the method name - it causes a
syntax error when I compile. Changing it to :: the compiler says that's
old
syntax. Removing it compiles fine if I don't try to implement the generic
IEnumerable too. Stumped! ;)
Click to expand...


You can rename one of the methods and use an explicit interface
implementation to tie it to the actual method of the interface it
implements. The following example renames IEnumerable<T>::GetEnumerator to
GetEnumeratorGen():


using namespace System;
using namespace System::Collections;

public ref class T sealed
: public IEnumerable
, public System::Collections::Generic::IEnumerable<int>
{
public:
virtual IEnumerator^ GetEnumerator() = IEnumerable::GetEnumerator
{
return nullptr;
}

virtual System::Collections::Generic::IEnumerator<int>^
GetEnumeratorGen()
= System::Collections::Generic::IEnumerable<int>::GetEnumerator
{
return nullptr;
}

};


You can find this documented on your VS2005 documentation under the heading:
Explicit Override of an interface member:
ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.VisualStudio.v80.en/dv_vccore/html/46f1f536-bf43-4311-9a17-ff2282e528a9.htm
 
KH said:
I can't seem to figure this one out... I've searched MSDN and Goog, and
made
my best guesses to no avail,, so help would be much appreciated!

public ref class T sealed
: public System::Collections::IEnumerable
, public System::Collections::Generic::IEnumerable<int>
{
// How to implement GetEnumerator() for both interfaces?
// Compiler complains that functions differ only in return type
// which I understand, but can't get the right syntax for explicit
// interface implementations...
};

Explicit interface implementations in .NET SDK show the following syntax:

private: virtual System::Collections::IEnumerator^
System.Collections.IEnumerable.GetEnumerator() sealed =
System::Collections::IEnumerable::GetEnumerator
{ /*function body*/ }
Click to expand...
I don't think that works with ambigious virtual functions. Just
rename both to different names and use explicit override specifications:

IEnumerator^ GetNongenericEnumerator() sealed =
IEnumerable::GetEnumerator { ... }
Generic::IEnumerator<int>^ GetGenericEnumerator() sealed =
Generic::IEnumerable<int>::GetEnumerator { ... }

-hg
 
Thanks! both of you


Tomas Restrepo (MVP) said:
KH,




You can rename one of the methods and use an explicit interface
implementation to tie it to the actual method of the interface it
implements. The following example renames IEnumerable<T>::GetEnumerator to
GetEnumeratorGen():


using namespace System;
using namespace System::Collections;

public ref class T sealed
: public IEnumerable
, public System::Collections::Generic::IEnumerable<int>
{
public:
virtual IEnumerator^ GetEnumerator() = IEnumerable::GetEnumerator
{
return nullptr;
}

virtual System::Collections::Generic::IEnumerator<int>^
GetEnumeratorGen()
= System::Collections::Generic::IEnumerable<int>::GetEnumerator
{
return nullptr;
}

};


You can find this documented on your VS2005 documentation under the heading:
Explicit Override of an interface member:
ms-help://MS.VSCC.v80/MS.MSDN.v80/MS.VisualStudio.v80.en/dv_vccore/html/46f1f536-bf43-4311-9a17-ff2282e528a9.htm
Click to expand...
 
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