22b4470f2a
Update all links to C++ Core Guidelines to `e49158a`.
Refresh done using the following script and some manual edits:
db76e34e74/personal/fred-tingaud/rspec/refresh-cppcoreguidelines.py
When re-using this script, be mindful that:
- it does not cover `shared_content`
- it does not properly escape inline code in links (e.g., "[=]" or "`mutex`es")
- it does not change `C++` to `{cpp}` in link titles.
Co-authored-by: Marco Borgeaud <marco.borgeaud@sonarsource.com>
83 lines
2.6 KiB
Plaintext
83 lines
2.6 KiB
Plaintext
== Why is this an issue?
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If you manage memory manually, it's your responsibility to ``++delete++`` all memory created with ``++new++``, and to make sure it's ``++delete++``d once and only once. Ensuring this is done is error-prone, especially when your function can have early exit points.
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Fortunately, the {cpp} language provides tools that automatically manage memory for you. Using them systematically makes the code simpler and more robust without sacrificing performance.
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This rule raises an issue when you use:
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* ``++new++`` - you should prefer a factory function that returns a smart pointer, such as ``++std::make_unique++`` or, if shared ownership is required, ``++std::make_shared++``,
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* ``++new[]++`` - you should prefer a container class, such as ``++std::vector++``,
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* ``++delete++`` or ``++delete[]++`` - if you followed the previous advice, there is no need to manually release memory.
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If your compiler does not support ``++make_unique++``, it's easy to write your own:
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----
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template<typename T, typename... Args>
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std::unique_ptr<T> make_unique(Args&&... args) {
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return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
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}
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----
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=== Noncompliant code example
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[source,cpp]
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----
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void f() {
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auto c = new Circle(0, 0, 5);
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c->draw();
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delete c;
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}
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----
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=== Compliant solution
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[source,cpp]
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----
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void f() {
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auto c = make_unique<Circle>(0, 0, 5);
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c->draw();
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unique_ptr<Circle> c2{new Circle(0, 0, 5)}; // Clumsy, but still compliant by exception
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}
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----
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=== Exceptions
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If the result of a new is immediately passed as an argument to a function, we assume that the function takes ownership of the newly created object, and won't raise an issue.
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== Resources
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* {cpp} Core Guidelines - https://github.com/isocpp/CppCoreGuidelines/blob/e49158a/CppCoreGuidelines.md#r11-avoid-calling-new-and-delete-explicitly[R.11: Avoid calling `new` and `delete` explicitly]
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* {cpp} Core Guidelines - https://github.com/isocpp/CppCoreGuidelines/blob/e49158a/CppCoreGuidelines.md#c149-use-unique_ptr-or-shared_ptr-to-avoid-forgetting-to-delete-objects-created-using-new[C.149: Use `unique_ptr` or `shared_ptr` to avoid forgetting to `delete` objects created using `new`]
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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=== Message
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Replace the use of "new" with an operation that automatically manages the memory.
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Rewrite the code so that you no longer need this "delete".
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'''
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== Comments And Links
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(visible only on this page)
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=== is related to: S5945
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=== on 9 Nov 2018, 16:33:19 Ann Campbell wrote:
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Double-check my edits please, [~loic.joly]
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endif::env-github,rspecator-view[]
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