CIRCCOLL Attributes Sample: Demonstrates a Collection/Enumeration

The CIRCCOLL attributes sample shows how to implement a collection/enumeration of objects using ATL.

The CIRCCOLL sample is the nonattributed version of this sample.

Security noteSecurity Note

This sample code is intended to illustrate a concept, and it shows only the code that is relevant to that concept. It may not meet the security requirements for a specific environment, and it should not be used exactly as shown. We recommend that you add security and error-handling code to make your projects more secure and robust. Microsoft provides this sample code "AS IS" with no warranties.

To get samples and instructions for installing them:

To access samples from Visual Studio

  • On the Help menu, click Samples.

    By default, these samples are installed in drive:\Program Files\Microsoft Visual Studio 10.0\Samples\.

  • For the most recent version of this sample and a list of other samples, see Visual Studio Samples on the MSDN Web site.

Building and Running the Sample

To build and run this sample

  1. Open the solution file circoll.sln.

  2. From the Build menu, click Build Solution.

  3. In Solution Explorer, right-click the CircCollClient project and select Set as StartUp Project.

  4. From the Debug menu, click Start.

  5. The Visual Basic form, Form1, will open. Click the button to activate the application.

How the Sample Works

Three object classes are implemented: the collection creator, the collection, and the object inside the collection. Only the collection creator has a coclass associated with it (see Circcoll.idl for the coclass declaration). The collection creator has a method to return a collection of circle objects. The collection object implements the Item, Count, and _NewItem methods, so that the object can be manipulated from Visual Basic using both the For...Next and For Each... syntax.


This sample uses the following attributes:

aggregatable, coclass, dual, emitidl, helpstring, id, in, module, noncreatable, object, out, pointer_default, progid, propget, propput, restricted, retval, support_error_info, threading, uuid, version


This sample uses the following keywords:

AddRef; ATLASSERT; ATLTRACE; BEGIN_COM_MAP; BEGIN_OBJECT_MAP; CComCoClass; CComObject::CreateInstance; CComObjectRoot; CComVariant; COM_INTERFACE_ENTRY; DECLARE_NOT_AGGREGATABLE; DECLARE_REGISTRY; END_COM_MAP; END_OBJECT_MAP; glBegin; glEnd; glNormal3d; glPolygonMode; glVertex2d; glVertex3d; IConnectionPointContainerImpl::FindConnectionPoint; IConnectionPointImpl::Advise; IDispatchImpl; ISupportErrorInfo; OBJECT_ENTRY; QueryInterface; Release; USES_CONVERSION; VariantCopy; VariantInit


Some of the samples, such as this one, have not been modified to reflect the changes in the Visual C++ wizards, libraries, and compiler, but still demonstrate how to complete your desired task.

See Also

Other Resources

ATL Attributes Samples