How to declare an enum in an .IDL file?

Question

I have a runtimeclass that I would like to add an enum to. I have tried the following syntax as suggested by the MSDN documentation here: https://learn.microsoft.com/en-ca/uwp/midl-3/intro

namespace my_project
{
    runtimeclass my_rt_class
    {        
        enum my_enum
        {
            first = 0,
            second = 1
        };
    }
}

However I get the following error from MIDL:

error MIDL2025: [msg]syntax error [context]: expecting an identifier near ";"

Whats the correct syntax for this? I am using version 10.0.17763.0 of the windows SDK.

score 5 · Accepted Answer · edited Jun 20 '20 at 09:12

You cannot nest enumerations in types. From the documentation you linked to:

The key organizational concepts in a MIDL 3.0 declaration are namespaces, types, and members. A MIDL 3.0 source file (an .idl file) contains at least one namespace, inside which are types and/or subordinate namespaces. Each type contains zero or more members.

Classes, interfaces, structures, and enumerations are types.

Fields, methods, properties, and events are examples of members.

Since enumerations are types, they must appear in a namespace. You will need to change your IDL to this:

namespace my_project
{
    enum my_enum
    {
        first = 0,
        second = 1
    };

    runtimeclass my_rt_class
    {        
    }
}

How to declare an enum in an .IDL file?

1 Answers1