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CIRCCOLL Attributes Sample: Demonstrates a Collection/Enumeration 

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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 provided to illustrate a concept and should not be used in applications or Web sites, as it may not illustrate the safest coding practices. Microsoft assumes no liability for incidental or consequential damages should the sample code be used for purposes other than as intended.

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

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