Commit e16d267

description: "Learn more about: Add a property"

ms.date: "11/09/2018"

f1_keywords: ["vc.codewiz.prop.overview", "vc.codewiz.prop.idlattributes"]

helpviewer_keywords: ["interfaces, adding properties", "properties [C++], adding to interfaces", "names, add property wizard", "IDL attributes, add property wizard", "stock properties, about stock properties", "stock properties"]

You can use the [add property wizard](#names-add-property-wizard) to add a method to an interface in your project.

**To add a property to your object:**

1. In [Class View](/visualstudio/ide/viewing-the-structure-of-code), right-click the name of the interface to which you want to add the property.

1. From the shortcut menu, choose **Add**, and then choose **Add Property**.

1. In the [add property wizard](#names-add-property-wizard), provide the information to create the property.

1. Specify any interface definition language (IDL) settings for the property in the [IDL attributes](#idl-attributes-add-property-wizard) page of the wizard.

1. Select **Finish** to add the property.

The `Get` and `Put` methods of the property are displayed as two icons in Class View, under the interface where it's defined. You can double-click either icon to view the property declaration in the .idl file.

- For ATL interfaces, the `Get` and `Put` functions are added to the .cpp file, and references to these functions are added to the .h file.

- For MFC dispinterfaces, if you select **Member variable** as the implementation type, a method and a variable are added to the class that implements it. If you select **Get/Set methods** as the implementation type, two methods are added to the class that implements it.

- [Names, add property wizard](#names-add-property-wizard)

- [IDL attributes, add property wizard](#idl-attributes-add-property-wizard)

- [Stock properties](#stock-properties)

Use this wizard to add a property to an interface.

- **Property type**

Sets the type of property you're adding. For MFC dispinterfaces, provide your own type or select from the predefined list. If you provide a stock implementation of a property, **Property type** is set to the stock type and is unavailable for change.

Sets the name of the property. For MFC dispinterfaces associated with ActiveX controls, you can supply your own name or you can select a stock property name from the predefined list. If you provide your own property name, the **Stock** implementation type is unavailable. See [stock properties](#stock-properties) for a description of the properties in the list.

|Interface type|Description|

|--------------------|-----------------|

|ATL dual interface, custom interface, and local custom interface|Provide a property name.|

|MFC dispinterface, MFC ActiveX control dispinterface|Provide a property name or select a stock property from the list. If you select a property from the list, the appropriate value appears in the **Property type** box. You can change this type, depending on your selection under **Implementation type**.|

- **Return type**

ATL interfaces only. Sets the return type for the property. For dual interfaces, `HRESULT` is always the return type, and this box is unavailable. For custom interfaces, you can select a return type from the list. `HRESULT` is still recommended, because it provides a standard way to return errors.

- **Variable name**

MFC dispinterfaces only. Available only if you specify **Member variable** under **Implementation type**. Sets the name of the member variable with which the property is associated. By default, the variable name is set to `m_`*PropertyName*. You can edit this name.

- **Notification function**

MFC dispinterfaces only. Available only if you specify **Member variable** under **Implementation type**. Sets the name of the notification function called if the property changes. By default, the name of the notification function is set to `On`*PropertyName*`Changed`. You can edit this name.

For MFC dispinterfaces. Available only if you specify **Get/Set methods** under **Implementation type**. Sets the name of the function to get the property. By default, the name of the `Get` function is set to `Get`*PropertyName*. You can edit this name. If you delete the name, the function [GetNotSupported](../mfc/reference/colecontrol-class.md#getnotsupported) is inserted into the interface dispatch map. The `Get`*PropertyName* function specifies that the property as readable.

- **Set function**

MFC dispinterfaces only. Available only if you specify **Get/Set methods** under **Implementation type**. Sets the name of the function to set the property. By default, the name of the `Set` function is set to `Set`*PropertyName*. You can edit this name. If you delete the name, the function [SetNotSupported](../mfc/reference/colecontrol-class.md#setnotsupported) is inserted into the interface dispatch map. The `Set`*PropertyName* function specifies that the property is writable.

- **Implementation type**

MFC dispinterfaces only. Specifies how to implement the property you're adding.

|Implementation type|Description|

|-------------------------|-----------------|

|**Stock**|Specifies a stock implementation for the property selected in **Property name**. The default. For more information, see [stock properties](#stock-properties).<br /><br /> If you specify **Stock**, then **Property type**, **Parameter type**, and **Parameter name** are dimmed.|

|**Member variable**|Specifies the property is added as a member variable. You can add custom properties or most stock properties as member variables. You can't specify **Member variable** for the `Caption`, `hWnd`, and `Text` properties.<br /><br /> Provides default names under **Variable name** and **Notification function**. You can edit this name.|

|**Get/Set methods**|Specifies the property is added as `Get`*PropertyName* and `Set`*PropertyName* functions, by default. These names appear under **Get function** and **Set function**.<br /><br /> You can change the default **Property type**, which passes a value for the Get function. You can specify parameters for the `Get` and `Set` functions.|

- **Get function**

- **Put function**

ATL interfaces only. Sets the property writable; that is, it creates the `Put` method for setting, or "putting," this property of the object. Select **Get**, **Put**, or both. If you select this option, you can choose from the following two ways to implement the method:

|Option|Description|

|------------|-----------------|

|**PropPut**|The [PropPut](../windows/attributes/propput.md) function returns a copy of the object. This is the default and the most common way to make the property writable.|

|**PropPutRef**|The [PropPutRef](../windows/attributes/propputref.md) function returns a reference to the object, rather than returning the copy of the object itself. Consider using this option for objects, such as large structs or arrays, that may have initialization overhead.|

- **Parameter attributes**

ATL interfaces only. Sets whether the parameter specified by **Parameter name** is `in`, `out`, both, or none.

|Option|Description|

|------------|-----------------|

|`in`|Indicates that the parameter is passed from the calling procedure to the called procedure.|

|`out`|Indicates that the pointer parameter is returned from the called procedure to the calling procedure (from the server to the client).|

- **Parameter type**

Sets the data type of the parameter. Select the type from the list.

- **Parameter name**

Sets the name of a parameter you're adding for the property, if the property has parameters. Once you select **Add**, the parameter name appears in **Parameter list**.

- **Parameter list**

Displays the list of attributes to be added to the property. Each item in the list consists of the parameter name, parameter type, and attributes. Use **Add** and **Remove** to update the list.

- **Add**

Adds the parameter you specify in **Parameter name** and **Parameter type** to the **Parameter list**. Select **Add** to add a parameter to the list.

- **Remove**

Removes the parameter you select in **Parameter list**.

- **Default property**

MFC dispinterface only. Sets this property as the default for the interface. An interface can have only one default property; once you specify the default property, for any other properties you add to the interface, this box is unavailable.

Use this page of the Add Property Wizard to specify any interface definition language (IDL) settings for the property.

- `id`

Sets the numerical ID that identifies the property. This option isn't available for properties of custom interfaces. See [id](/windows/win32/Midl/id) in the *MIDL Reference*.

- `helpcontext`

Specifies a context ID that lets the user view information about this property in the Help file. See [helpcontext](/windows/win32/Midl/helpcontext) in the *MIDL Reference*.

- `helpstring`

Specifies a character string that's used to describe the element to which it applies. By default, it's set to **`property`**&nbsp;*Property&nbsp;name*. See [helpstring](/windows/win32/Midl/helpstring) in the *MIDL Reference*.

Not all options are available to all property types.

|Option|Description|

|------------|-----------------|

|`bindable`|Indicates that the property supports data binding. See [bindable](/windows/win32/Midl/bindable) in the *MIDL Reference*. For the stock implementation of the property, this option is set by default and is unchangeable.|

|`defaultbind`|Indicates that this single, bindable property best represents the object. See [defaultbind](/windows/win32/Midl/defaultbind) in the *MIDL Reference*.|

|`displaybind`|Indicates that this property should be displayed to the user as bindable. See [displaybind](/windows/win32/Midl/displaybind) in the *MIDL Reference*.|

|`immediatebind`|Indicates that the database will be notified immediately of all changes to this property of a data-bound object. See [immediatebind](/windows/win32/Midl/immediatebind) in the *MIDL Reference*.|

|`defaultcollelem`|Indicates that the property is an accessor function for an element of the default collection. See [defaultcollelem](/windows/win32/Midl/defaultcollelem) in the *MIDL Reference*.|

|`nonbrowsable`|Tags an interface or dispinterface member that shouldn't be displayed in a properties browser. See [nonbrowsable](/windows/win32/Midl/nonbrowsable) in the *MIDL Reference*.|

|`requestedit`|Indicates that the property supports the `OnRequestEdit` notification. See [requestedit](/windows/win32/Midl/requestedit) in the *MIDL Reference*. For the stock implementation of the property, this option is set by default and is unchangeable.|

|`source`|Indicates that a member of the property is a source of events. See [source](/windows/win32/Midl/source) in the *MIDL Reference*.|

|`hidden`|Indicates that the property exists but shouldn't be displayed in a user-oriented browser. See [hidden](/windows/win32/Midl/hidden) in the *MIDL Reference*.|

|`restricted`|Specifies that the property can't be called arbitrarily. See [restricted](/windows/win32/Midl/restricted) in the *MIDL Reference*.|

|`local`|Specifies to the MIDL compiler that the property isn't remote. See [local](/windows/win32/Midl/local) in the *MIDL Reference*.|

If you're adding a property to an MFC dispinterface using the [add property wizard](#idl-attributes-add-property-wizard), you can choose a stock property from the **Property name** list in the [Names](#names-add-property-wizard) page of the wizard. These properties are as follows:

|Property name|Description|

|-------------------|-----------------|

|`Appearance`|Returns or sets a value that determines the appearance of the control. The control's `Appearance` property can include or omit three-dimensional display effects. This property is an ambient read/write property.|

|`BackColor`|Returns or sets the control's ambient `BackColor` property to either a palette (RGB) color or a predefined system color. By default, its value corresponds to the foreground color of the control's container. This property is an ambient read/write property.|

|`BorderStyle`|Returns or sets the border style for a control. This property is a read/write property.|

|`Caption`|Returns or sets the control's `Caption` property. The caption is the title of the window. `Caption` has no **Member variable** implementation type.|

|`Enabled`|Returns or sets the control's `Enabled` property. An enabled control can respond to user-generated events.|

|`Font`|Returns or sets the control's ambient font. Null if the control has no font.|

|`ForeColor`|Returns or sets the control's ambient `ForeColor` property.|

|`hWnd`|Returns or sets the control's `hWnd` property. `hWnd` has no **Member variable** implementation type.|

|`ReadyState`|Returns or sets the control's `ReadyState` property. A control can be uninitialized, initialized, loading, interactive, or complete. For more information, see [READYSTATE](/previous-versions/aa768362\(v=vs.85\)) in the *Internet SDK*.|

|`Text`|Returns or sets the text contained in a control. `Text` has no **Member variable** implementation type.|