id

[id(id-num) [,optional-attribute-list]] return-type function-name

Example

Interface IKnown : IUnknown
{
properties:
[id(90), propget, helpstring("A meaningful comment."]
        long Func1(void);
. . .
}

Remarks

The id attribute specifies a DISPID for a member function (either a property or a method, in an interface or dispinterface). You use the id attribute when you want to assign a standard DISPID (like DISPID_VALUE, DISPID_NEWENUM etc.) to a method or property, or when you implement your own IDispatch::Invoke instead of delegating to DispInvoke/ITypeInfo::Invoke.

If you do not use the id attribute on an interface, the MIDL compiler will assign a DISPID for you. However, when you specify a dispinterface by using properties and methods you must specify a DISPID for every property and method.

The id-num is a 32-bit integral value in the following format:

Bits Value
0–15 Offset. Any value is permissible.
16–21 The nesting level of this typeinfo in the inheritance hierarchy. For example:
interface mydisp : IDispatch

The nesting level of IUnknown is 0, IDispatch is 1, and mydisp is 2.
22–25 Reserved; must be zero
26–28 DISPID value.
29 True if this is the member ID for a FuncDesc; otherwise False.
30–31 Must be 01.

Negative IDs are reserved for use by OLE Automation.

See Also

interface, dispinterface, ODL File Syntax, ODL File Example, Generating a Type Library With MIDL