Скачать или смотреть Resolving Call to Implicitly Deleted Copy Constructor Error in C+ + Classes

Learn how to fix the `Call to implicitly deleted copy constructor` error when using classes with `std::thread` members in C+ + .
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This video is based on the question https://stackoverflow.com/q/64650981/ asked by the user 'Marcel_marcel1991' ( https://stackoverflow.com/u/3850759/ ) and on the answer https://stackoverflow.com/a/64651285/ provided by the user 'john' ( https://stackoverflow.com/u/882003/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Call to Implicitly Deleted Copy Constructor Error

If you've encountered the frustrating error message regarding the implicitly deleted copy constructor while working with classes in C+ + , you're not alone. This issue commonly arises when a class contains a member of type std::thread, which cannot be copied. In this post, we’ll explore a minimal example to understand the error and provide you with a straightforward solution.

The Problem Explained

In a typical C+ + setup, if you have a class containing a std::thread member and then try to use this class as a member of another class, the compiler may throw an error stating that the implicit copy constructor has been deleted. The crux of the issue lies in how the copy constructors and initializations are managed.

Example Setup

Consider the following classes:

[[See Video to Reveal this Text or Code Snippet]]

In the code above, the VideoSender class includes a std::thread member named encoderThread. When you try to instantiate RemoteCom like this:

[[See Video to Reveal this Text or Code Snippet]]

you will run into the implicit copy constructor error. This statement tries to create a temporary RemoteCom object and then copy it into com, necessitating a copy constructor for RemoteCom, which in turn needs to copy the VideoSender. Since VideoSender has a non-copyable std::thread, the compiler denies this operation.

Solution to the Error

The solution is quite simple: instead of using the copy constructor for RemoteCom, which inadvertently requires a copy constructor for its members, you should directly invoke the default constructor for RemoteCom.

Updated Initialization

Here’s how to correctly instantiate RemoteCom without running into the implicit copy constructor issue:

[[See Video to Reveal this Text or Code Snippet]]

Why This Works

Direct Initialization: By using RemoteCom com;, you’re directly calling the default constructor of RemoteCom without creating a temporary object that needs to be copied. This circumvents the need for any copy constructors entirely.

No Complex Copying: This approach avoids the complexities that arise from attempting to copy objects that contain non-copyable members like std::thread.

Conclusion

In conclusion, if your C+ + classes are generating the Call to implicitly deleted copy constructor error when you try to use one class with a std::thread member inside another class, simply changing the way you instantiate the second class can solve your problem. Always prefer direct initialization when dealing with classes that include non-copyable members.

Make these small adjustments and you’ll keep your code clean and error-free. Happy coding!