c++ - Code simpler than lambda for a call in constructor that uses an output parameter function for initializing a const member

In the header, I have

class CSomeClass
{
    const GUID m_guid;


public:
    CSomeClass();
///...
}

And in the source file

CSomeClass::CSomeClass()

    , m_guid(
        []() {
        GUID g;
        ::CoCreateGuid(&g);
        return g;
        }()
    )
{
}

As you know Guids can be used as identifications not meant to be changed. Given the ::CocreateGuid() function provides what I want as an output parameter, instead of returning it, I cannot use directly a simple call to the function for initializing the m_guid member field, that is constant.

So, a consequence of its constness, is that it must be initialized before the opening bracket in initializer list, and therefore not be simply assigned with a call to ::CocreateGuid() in the constructor body.

Is there a simpler way to initialize it than this lambda expression?

Answer

When the lambda expression is correct, I would use a helper function for that:

GUID create_guid()

{
    GUID g;
    ::CoCreateGuid(&g);
    return g;
}

CSomeClass::CSomeClass() : m_guid(create_guid()) {}

In addition, create_guid() has a meaning by itself and could be reused (even if making it a implementation detail is possible/correct).