stack allocated sf::Music

[lorence30]

why cant I allocated sf::Music on stack

heres my code:

class Track
{
   public:
       Track(const std::string&);
       const std::string& getName() const;
       const sf::Music& getAudio() const;
   private:
       std::string name;
       sf::Music audio;
};

this spits out:
error: use of deleted function 'sf::Music::Music(const sf::Music&)'
error: use of deleted function 'sf::SoundStream::SoundStream(const sf::SoundStream&)'
error: use of deleted function 'sf::Mutex::Mutex(const sf::Mutex&)'
error: 'sf::NonCopyable::NonCopyable(const sf::NonCopyable&)' is private NonCopyable(const NonCopyable&);
error: use of deleted function 'sf::InputSoundFile::InputSoundFile(const sf::InputSoundFile&)'
 error: use of deleted function 'sf::Mutex::Mutex(const sf::Mutex&)'
 class SFML_AUDIO_API Music : public SoundStream
 error: use of deleted function 'Track::Track(Track&&)'

but when i allocate it on heap like this:

class Track
{
   public:
       Track(const std::string&);
       const std::string& getName() const;
       const sf::Music& getAudio() const;
   private:
       std::string name;
       sf::Music* audio;
};

it works fine

TIA.

[eXpl0it3r]

Since sf::Music has an sf::Mutex as member variable which is sf::NonCopyable the music object becomes non-copyable as well. This means you either have to implement a copy constructor and handle the "copying" of the music object manually, or you just don't copy your Track class.

For the SFML Team: Shouldn't we derive sf::Music from sf::NonCopyable to make it more explicit?

[Nexus]

You can generally solve such problems by separating resources (like music) and their clients (like the "track" in your example), and let the latter reference the former.

For the SFML Team: Shouldn't we derive sf::Music from sf::NonCopyable to make it more explicit?

I think we should. There won't even be any overhead (EBO).

[lorence30]

thanks guys


im using QT and SFML audio , i was trying to inherit sf::Music to my Track class and just add a feature for std::string name so i can keep track of the name of the song, so if the user double clicks the song i will just find the name matches with the name being clicked then play the Track::audio

[Nexus]

You shouldn't use inheritance for this purpose, most of the SFML classes are not designed as a base class. Just use composition.

[Hapax]

i was trying to inherit sf::Music to my Track class and just add a feature for std::string name so i can keep track of the name of the song

I think using the word "inherit" here is incorrect. It's probably a genuine language mistake.
It looks like you're writing a "wrapper" class that includes the music object and also extra information.
"Inheritance", though, would look something like this (DO NOT TRY THIS!): class Track : public sf::Music