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Closes #1748

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Herb Sutter 2021-02-18 11:20:09 -08:00
parent a97be2d528
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1 changed files with 12 additions and 16 deletions
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CppCoreGuidelines.md
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@ -4669,30 +4669,26 @@ If you don't want a generated default function, suppress it with `=delete`.
##### Example, good
When a destructor needs to be declared just to make it `virtual`, it can be
defined as defaulted. To avoid suppressing the implicit move operations
they must also be declared, and then to avoid the class becoming move-only
(and not copyable) the copy operations must be declared:
defined as defaulted.
class AbstractBase {
public:
virtual ~AbstractBase() = default;
AbstractBase(const AbstractBase&) = default;
AbstractBase& operator=(const AbstractBase&) = default;
AbstractBase(AbstractBase&&) = default;
AbstractBase& operator=(AbstractBase&&) = default;
virtual ~AbstractBase() = default;
// ...
};
Alternatively to prevent slicing as per [C.67](#Rc-copy-virtual),
the copy and move operations can all be deleted:
To prevent slicing as per [C.67](#Rc-copy-virtual),
`=delete` the copy and move operations and add a `clone`:
class ClonableBase {
public:
virtual unique_ptr<ClonableBase> clone() const;
virtual ~ClonableBase() = default;
ClonableBase(const ClonableBase&) = delete;
ClonableBase& operator=(const ClonableBase&) = delete;
ClonableBase(ClonableBase&&) = delete;
ClonableBase& operator=(ClonableBase&&) = delete;
virtual unique_ptr<ClonableBase> clone() const;
virtual ~ClonableBase() = default;
ClonableBase(const ClonableBase&) = delete;
ClonableBase& operator=(const ClonableBase&) = delete;
ClonableBase(ClonableBase&&) = delete;
ClonableBase& operator=(ClonableBase&&) = delete;
// ... other constructors and functions ...
};
Defining only the move operations or only the copy operations would have the