Add an IDL method

The Add IDL Method wizard adds a method to an Interface Definition Library (IDL) interface, such as in an ATL project that contains an IDL file. This wizard isn't available in projects that support MFC.

This wizard differs from the Add method wizard and the Add IDL MFC method wizard in the following ways:

• The Add method wizard adds a method to an interface in your project and can update the class associated with the interface.
• The Add IDL MFC method wizard is specific to MFC, ActiveX, or ATL projects that support MFC.

Add a method to your IDL interface

1. On the View menu, select Class View.

2. In the Class View pane, expand the project node to display the IDL interface (.idlfile) to which you want to add the method.

3. Right-click the name of the interface.

4. On the shortcut menu, select Add > Add Method.

5. In the Add IDL Method wizard, provide the information to create the method.

6. Select OK to add the method.

User Interface element list

The following section describes the wizard interface that you'll use to add a method:

• Method name

  Provide a name for the method.

• Return type

  The data type returned by the method. The standard way to return error codes from methods defined in an interface is with an HRESULT.

  The following table describes the different kinds of interfaces that you can add a method to, and the allowed return type. For dual and custom interfaces, the return type must be HRESULT and the wizard won't allow you to change it.

  Interface kind	Return type
  Dual interface	HRESULT. Unchangeable.
  Custom interface	HRESULT. Unchangeable.
  Local custom interface	Provide your own return type or select it from the drop-down list.
  Dispinterface	Provide your own return type or select it from the drop-down list.

• Parameters

  Displays the method's parameters, modifiers, and types.

• +

  Add a parameter. In Parameters, type the parameter type, name, and any modifiers. For example, [in] int i, and choose OK.

• x

  Removes the selected parameter from the Parameters list.

• Infer in/out parameters values from types

  Inserts the [in] or [out] attribute based on the parameter's type.

• Set the last parameter as the return value (retval)

  The last parameter will be treated as the method's return value.

• Attributes

  The following attributes are also described in the MIDL Reference.

  • id

    Sets the numeric ID that identifies the method. For more information, see id.

  • call_as

    Specifies the name of the remote method to map to this local method. For more information, see call_as.

  • helpcontext

    Specifies a context ID that lets the user view information about this method in the Help file. For more information, see helpcontext.

  • helpstring

    Specifies the character string used to describe the element to which it applies. For more information, see helpstring.

• Additional attributes

  • hidden

    Indicates that the item exists but shouldn't be displayed in a user-oriented browser. For more information, see hidden.

  • local

    Specifies that an interface or function isn't remote. For more information, see local.

  • restricted

    Specifies that a library, or member of a module, interface, or dispinterface can't be called arbitrarily. For more information, see restricted.

  • source

    Indicates that a member of a coclass, property, or method is a source of events. For a member of a coclass, this attribute means that the member is called rather than implemented. For more information, see source.

See also

Add a method wizard
Add an IDL MFC method wizard