AC_DISABLE_MOVE¶

Reference¶

#include <actl/lifetime/move/AC_DISABLE_MOVE.hpp>

AC_DISABLE_MOVE(type)¶

Macro to be used inside a class to disable its move and copy constructor and assignment operator. For example,

class mutex {
public:
    mutex() = default;
    AC_DISABLE_MOVE(mutex)
};

mutex a;
mutex b = a;            // compilation error
mutex c = std::move(a); // compilation error

Default constructor is also disabled unless defined explicitly.

To disable only copy and not move, use AC_DISABLE_COPY.

See tests at tests/lifetime/move/AC_DISABLE_MOVE.cpp

Design¶

AC_DISABLE_MOVE has effect similar to boost::noncopyable. However, the base class approach of boost::noncopyable has multiple issues:

Extra base class makes class hierarchy more complex, which can reduce dynamic_cast efficiency.
If multiple empty classes derive from the same boost::noncopyable then their storage cannot be merged together using EBO.
Namespace of the base class is added to ADL, which adds extra work for the compiler and can have surprising effects.
Aggregate initialization requires extra braces for the base class: Derived{{}, members...}.
operators == and <=> cannot be defaulted, that is the following code won’t compile
```
bool operator==(const Derived&) const = default;
```