替代 operator()() 重载？ || 直接会员访问

Question

I would like to wrap C types into a CPP class for better memory handling. For instance the below code snippet shows roughly what I would like to do:

class TJCompressor
{
public:
    TJCompressor()
        : m_tjInstance(tjInitCompress())
    {
        if (m_tjInstance == nullptr)
            throw std::runtime_error("Could not create a TJ compressor instance");
    }
    ~TJInstance()
    {
        tjDestroy(m_tjInstance);
    }

    const tjhandle& operator()() const
    {
        return m_tjInstance;
    }

private:
    tjhandle m_tjInstance = nullptr;
};

However, now I need to access the actual tjhandle through operator()() and I would prefer to get rid of this.

TJCompressor compressor;
tjDecompressHeader3(decompressor(), ... );  // works as expected
tjDecompressHeader3(decompressor, ... );    // preferred way of doing it

I am pretty sure that this is achievable but I somehow can't find anything about how to do it.

Answer 1

What you want I think is a conversion operator.... something that looks like

operator const tjhandle & () const { return m_tjInstance; }

you will then be able to call your function as

tjDecompressHeader3(decompressor, ...)

More information can be found here: https://en.cppreference.com/w/cpp/language/cast_operator