# 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 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.

# 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.

# Attributes

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

# Keywords

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

Note
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.