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[GSL.view] Make wording around null pointers and null references more precise.

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Thomas Köppe
2015-10-03 16:09:03 +01:00
parent 0fc6a6d6db
commit 7143050ef6
1 changed files with 10 additions and 10 deletions
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CppCoreGuidelines.md
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@@ -12171,23 +12171,23 @@ References are never owners.
The names are mostly ISO standard-library style (lower case and underscore): The names are mostly ISO standard-library style (lower case and underscore):
* `T*` // The `T*` is not an owner, may be `nullptr` (Assumed to be pointing to a single element) * `T*` // The `T*` is not an owner, may be null; assumed to be pointing to a single element.
* `char*` // A C-style string (a zero-terminated array of characters); can be `nullptr` * `char*` // A C-style string (a zero-terminated array of characters); may be null.
* `const char*` // A C-style string; can be `nullptr` * `const char*` // A C-style string; may be null.
* `T&` // The `T&` is not an owner, may not be `&(T&)*nullptr` (language rule) * `T&` // The `T&` is not an owner, must not be `*static_cast<T*>(nullptr)` (language rule; there are no "null references").
The "raw-pointer" notation (e.g. `int*`) is assumed to have its most common meaning; that is, a pointer points to an object, but does not own it. The "raw-pointer" notation (e.g. `int*`) is assumed to have its most common meaning; that is, a pointer points to an object, but does not own it.
Owners should be converted to resource handles (e.g., `unique_ptr` or `vector<T>`) or marked `owner<T*>` Owners should be converted to resource handles (e.g., `unique_ptr` or `vector<T>`) or marked `owner<T*>`
* `owner<T*>` // a `T*`that owns the object pointed/referred to; can be `nullptr` * `owner<T*>` // a `T*`that owns the object pointed/referred to; may be `nullptr`.
* `owner<T&>` // a `T&` that owns the object pointed/referred to * `owner<T&>` // a `T&` that owns the object pointed/referred to.
`owner` is used to mark owning pointers in code that cannot be upgraded to use proper resource handles. `owner` is used to mark owning pointers in code that cannot be upgraded to use proper resource handles.
Reasons for that include Reasons for that include:
* cost of conversion * Cost of conversion.
* the pointer is used with an ABI * The pointer is used with an ABI.
* the pointer is part of the implementation of a resource handle. * The pointer is part of the implementation of a resource handle.
An `owner<T>` differs from a resource handle for a `T` by still requiring an explicit `delete`. An `owner<T>` differs from a resource handle for a `T` by still requiring an explicit `delete`.