attributes

The helpstring, helpcontext, hidden, uuid, and versionattributes are accepted before dispinterface. Attributes (including the brackets) can be omitted, except for the uuid attribute, which is required.

intfname

The name by which the dispinterface is known in the type library. This name must be unique within the type library.

interfacename

(Syntax 2) The name of the interface to declare as an IDispatchinterface.

proplist

(Syntax 1) An optional list of properties supported by the object, declared in the form of variables. This is the short form for declaring the property functions in the methods list. See the comments section for details.

methlist

(Syntax 1) A list comprising a function prototype for each method and property in the dispinterface. Any number of function definitions can appear in methlist. A function in methlist has the following form:

[ attributes ]  returntype  methname ( params );

The following attributes are accepted on a method in a dispinterface:

• helpstring
  
  
• helpcontext
  
  
• string(for compatibility with the Interface Definition Language)
  
  
• bindable
  
  
• defaultbind
  
  
• displaybind
  
  
• propget
  
  
• propput
  
  
• propputref
  
  
• vararg
  
  

If varargis specified, the last parameter must be a safe array of VARIANT type.

The parameter list is a comma-delimited list, each element of which has the following form:

[ attributes ]  type  paramname

The type can be any declared or built-in type, or a pointer to any type. Attributes on parameters are in, out, optional, and string.

If optionalis specified, it must only be specified on the right-most parameters, and the types of those parameters must be VARIANT.

Method functions are specified exactly as described in a module statement except that the entry attribute is not allowed.

Stdole2.tlb must be imported, because a dispinterface inherits from IDispatch.

Properties can be declared either in the properties or methods lists. Declaring properties in the properties list does not indicate the type of access the property supports ( get, put, or putref).

Specify the readonlyattribute for properties that do not support putor putref.

If the property functions are declared in the methods list, functions for one property will all have the same ID.

Using Syntax 1, the properties: and methods: tags are required. The idattribute is also required on each member. For example:

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properties: [id(0)] int Value; // Default property. methods: [id(1)] void Show();

Unlike interface members, dispinterface members cannot use the retvalattribute to return a value in addition to an HRESULT error code. The lcidattribute is also invalid for dispinterfaces because Invokepasses a locale ID (LCID). However, it is possible to declare an interface again that uses these attributes.

Using Syntax 2, interfaces that support IDispatchand are declared earlier in an Object Definition Language (ODL) script can be redeclared as IDispatchinterfaces as follows.

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dispinterface helloPro { interface hello; };

This example declares all of the members of the Hello sample and all of the members that it inherits to support IDispatch.

In this case, if Hello was declared earlier with lcidand retvalmembers that returned HRESULTs, MkTypLib would remove each lcidparameter and HRESULTreturn type, and instead mark the return type as that of the base type of the retvalparameter.

The properties and methods of a dispinterface are not part of the VTBL of the dispinterface. Consequently, CreateStdDispatchand DispInvokecannot be used to implement Invoke.

The dispinterface is used when an application needs to expose existing non-VTBL functions through Automation. These applications can implement Invokeby examining the dispidMemberparameter and directly calling the corresponding function.