title: "ATL Collections and Enumerators | Microsoft Docs"

ms.custom: ""

ms.date: "11/04/2016"

ms.technology: ["cpp-atl"]

ms.topic: "conceptual"

dev_langs: ["C++"]

helpviewer_keywords: ["enumerator interfaces", "collections, ATL classes", "enumerators, ATL classes", "collection interfaces"]

ms.assetid: b2d37119-3ab2-4e0a-b65b-f377f07e4098

author: "mikeblome"

ms.author: "mblome"

ms.workload: ["cplusplus"]

A `collection` is a COM object that provides an interface that allows access to a group of data items (raw data or other objects). An interface that follows the standards for providing access to a group of objects is known as a *collection interface*.

At a minimum, collection interfaces must provide a **Count** property that returns the number of items in the collection, an **Item** property that returns an item from the collection based on an index, and a `_NewEnum` property that returns an enumerator for the collection. Optionally, collection interfaces can provide **Add** and **Remove** methods to allow items to be inserted into or deleted from the collection, and a **Clear** method to remove all items.

An `enumerator` is a COM object that provides an interface for iterating through items in a collection. Enumerator interfaces provide serial access to the elements of a collection via four required methods: `Next`, **Skip**, **Reset**, and `Clone`.

You can learn more about enumerator interfaces by reading about the archetypal (but entirely imaginary) [IEnumXXXX](https://msdn.microsoft.com/library/ms680089.aspx) interface.

[ATL Collection and Enumerator Classes](../atl/atl-collection-and-enumerator-classes.md)

Briefly describes and provides links to the ATL classes that will help you implement collections and enumerators.

[Design Principles for Collection and Enumerator Interfaces](../atl/design-principles-for-collection-and-enumerator-interfaces.md)

Discusses the different design principles behind each type of interface.

[Implementing a C++ Standard Library-Based Collection](../atl/implementing-an-stl-based-collection.md)

An extended example that walks you through the implementation of a C++ Standard Library-based collection.

[ATL](../atl/active-template-library-atl-concepts.md)

Provides links to conceptual topics on how to program using the Active Template Library.

[ATLCollections Sample](../visual-cpp-samples.md)

A sample that demonstrates the use of `ICollectionOnSTLImpl` and `CComEnumOnSTL`, and the implementation of custom copy policy classes.

[Concepts](../atl/active-template-library-atl-concepts.md)

title: "ATL COM Desktop Components | Microsoft Docs"

ms.custom: ""

ms.date: "11/04/2016"

ms.technology: ["cpp-atl"]

ms.topic: "conceptual"

dev_langs: ["C++"]

helpviewer_keywords: ["ATL, reference", "ATL, about ATL"]

ms.assetid: 291f38d1-d2de-4687-86a9-99b4fd35706c

author: "mikeblome"

ms.author: "mblome"

ms.workload: ["cplusplus"]

The ATL Reference documents the Active Template Library (ATL), a set of template-based C++ classes that simplify the programming of Component Object Model (COM) objects. To fully take advantage of ATL, a working familiarity with COM is highly recommended.

[ATL Class Overview](../atl/atl-class-overview.md)

Provides links to and brief descriptions of the ATL classes organized by category.

[ATL Classes and structs](../atl/reference/atl-classes.md)

Provides reference material on the classes and structs organized alphabetically.

[ATL Functions](../atl/reference/atl-functions.md)

Provides reference material on the global functions organized alphabetically. Includes topics organizing the functions into categories.

[ATL Global Variables](../atl/reference/atl-global-variables.md)

Provides reference material on the global variables organized alphabetically.

[ATL Macros](../atl/reference/atl-macros.md)

Provides reference material on the macros organized alphabetically. Includes topics organizing the macros into categories.

[ATL Typedefs](../atl/reference/atl-typedefs.md)

Provides reference material on the typedefs organized alphabetically

[Worker Archetype](../atl/reference/worker-archetype.md)

Provides a links to the ATL Worker archetype.

[Obsolete ATL Topics](http://msdn.microsoft.com/en-us/7af0223d-148e-4a4c-bf9c-3e916a3b67ec)

Provides reference material on the classes, macros, and functions that are obsolete or deprecated.

[ATL](../atl/active-template-library-atl-concepts.md)

Provides topics on how to program using the Active Template Library (ATL).

[ATL Tutorial](../atl/active-template-library-atl-tutorial.md)

Leads you through the creation of a control and demonstrates some ATL fundamentals in the process.

[ATL Samples](../visual-cpp-samples.md)

Sample code that shows how to use ATL to write COM objects.

[OLE DB Templates](../data/oledb/ole-db-templates.md)

Provides reference material for the OLE DB consumer and provider templates, a set of template classes that implement many commonly used OLE DB interfaces.

title: "ATL Support for DHTML Controls | Microsoft Docs"

ms.custom: ""

ms.date: "11/04/2016"

ms.technology: ["cpp-atl"]

ms.topic: "conceptual"

dev_langs: ["C++"]

helpviewer_keywords: ["HTML controls, ATL support", "DHTML controls, ATL support", "DHTML controls"]

ms.assetid: 4ba98098-da5d-4362-96ad-8372f816c307

author: "mikeblome"

ms.author: "mblome"

ms.workload: ["cplusplus"]

Using ATL, you can create a control with Dynamic HTML (DHTML) capability. An ATL DHTML control:

- Hosts the WebBrowser control.

- Specifies, using HTML, the user interface (UI) of the DHTML control.

- Accesses the WebBrowser object and its methods through its interface, [IWebBrowser2](https://msdn.microsoft.com/library/aa752127.aspx).

- Manages communication between C++ code and HTML.

A DHTML control is similar to any other ATL control, except the DHTML control includes an additional dispatch interface. See the figure in [Identifying the Elements of the DHTML Control Project](../atl/identifying-the-elements-of-the-dhtml-control-project.md) for an illustration of the interfaces provided in the default DHTML project.

You can view the ATL DHTML control in a Web browser or other container, such as the ActiveX Control Test Container.

[Identifying the Elements of the DHTML Control Project](../atl/identifying-the-elements-of-the-dhtml-control-project.md)

Describes the elements of a DHTML control project.

[Calling C++ Code from DHTML](../atl/calling-cpp-code-from-dhtml.md)

Provides an example of calling C++ code from a DHTML control.

[Creating an ATL DHTML Control](../atl/creating-an-atl-dhtml-control.md)

Lists the steps for creating a DHTML control.

[Testing the ATL DHTML Control](../atl/testing-the-atl-dhtml-control.md)

Shows how to build and test the initial DHTML control project.

[Modifying the ATL DHTML Control](../atl/modifying-the-atl-dhtml-control.md)

Shows how to add some functionality to the control.

[Testing the Altered ATL DHTML Control](../atl/testing-the-modified-atl-dhtml-control.md)

Shows how to build and test the control's added functionality.

[ATL](../atl/active-template-library-atl-concepts.md)

Provides links to conceptual topics on how to program using the Active Template Library.

- [CComSafeArray](../atl/reference/ccomsafearray-class.md) This class is a wrapper for the [SAFEARRAY Data Type](http://msdn.microsoft.com/en-us/9ec8025b-4763-4526-ab45-390c5d8b3b1e) structure.

- [CComSafeArrayBound](../atl/reference/ccomsafearraybound-class.md) This class is a wrapper for a [SAFEARRAYBOUND](http://msdn.microsoft.com/en-us/303a9bdb-71d6-4f14-8747-84cf84936c6d) structure.

The following class provides support for dual interfaces:

- [IDispatchImpl](../atl/reference/idispatchimpl-class.md) Implements the `IDispatch` portion of a dual interface. For more information, see [Implementing the IDispatch Interface](http://msdn.microsoft.com/en-us/0e171f7f-0022-4e9b-ac8e-98192828e945).

[Class Overview](../atl/atl-class-overview.md)

The following class indicates how error information is handled:

- [ISupportErrorInfoImpl](../atl/reference/isupporterrorinfoimpl-class.md) Determines whether the object supports the [IErrorInfo](http://msdn.microsoft.com/en-us/4dda6909-2d9a-4727-ae0c-b5f90dcfa447) interface. **IErrorInfo** allows error information to be propagated back to the client.

[Class Overview](../atl/atl-class-overview.md)