Cpp on Sea 2022

[robertapplin]

Universal/Forwarding References

• l-value (locator value) is a value found at a memory location.
• pr-value (pure r-value) is all literals except strings, often seen on the rhs of an expression.
• x-value (exclusive value) is an expiring value like std::move(s)="Hello".
• Returning a variable by const value can sometimes cause a copy operation, as is not the case when returning by value. This is for the same reason you might create a constructor that has arguments taken by value (i.e. prevents copy for pr-values and instead does a move).
• Move is a static cast operation! std::move(x) = static_cast<T &&>(x)
• An example universal/forwarding reference:

  template <typename T>
  void callFoo(T&& x) {
  foo(std::forward<T>(x));
  }

• decltype(auto) can be used as the return value for perfect returning

A Practical Approach to Error Handling

• Use noexcept whenever possible when not expecting an exception
• Assert aggressively with assert (to ensure you stay on a narrow path). Never terminate if an assertion fails, as the assertion might be wrong (due to human error or assumptions). The assumptions made by a developer are also documented when it comes to trying to fix a problem caused by an assertion.
• Check everything, including every API call.
• Keep the set of code paths small, and possible program states small. Avoid throwing too many exceptions as they open up more code paths.
• Error handling: If possible, fixing an issue, rather than showing a message box, is a much favoured approach to error handling.

Aliasing

• This is where two variables, which refer to the same memory location, are used together causing interference. Memory can be modified causing unexpected values when a variable is used for a second time.
• Avoid aliasing by:
  • passing arguments by value
  • documenting your codes aliasing assumptions
  • writing defensive code through assert statements,
• The restrict keyword tells the compiler that aliasing is undefined behaviour.

Replacing Legacy Systems - Keys to success

TODO

Code smells

• Premature generalisation is when code is extended and over-complicated due to future notions of what will be included in the code (with no solid plans to actually implement them yet). It violates the KISS principle, and means the code is harder to maintain and requires more tests.
• Build smells - lack of tooling like profilers, static analysis and sanitizers.
• Violating Rule of 5 - a handle is most likely being shared between resources in a class that defines a destructor. Therefore, it is expected that a copy constructor and copy assignment operator will also need implementing (Rule of 3).

https://sourcemaking.com/refactoring/smells

Other

• Avoid using shared_ptr due to locking considerations, unless using a shared_ptr<const T>.
• Creating a strong type (inheriting a type to create a new strong type) is preferred over the using statement.
• Lectures used std::optional, std::span, cpp20 requires, pipe operator used frequently with cpp20 views and ranges.
• Learn more about address sanitizers.
• Compiler Explorer website was often used during the talks - might be useful.

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had activity in 6 months. It will be closed in 7 days if no further activity occurs. Allowing issues to close as stale helps us filter out issues which can wait for future development time. All issues closed by stale bot act like normal issues; they can be searched for, commented on or reopened at any point. If you'd like a closed stale issue to be considered, feel free to either re-open the issue directly or contact a developer. To extend the lifetime of an issue please comment below, it helps us see that this is still affecting you and you want it fixed in the near-future. Extending the lifetime of an issue may cause the development team to prioritise it over other issues, which may be closed as stale instead.

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had activity in 6 months. It will be closed in 7 days if no further activity occurs. Allowing issues to close as stale helps us filter out issues which can wait for future development time. All issues closed by stale bot act like normal issues; they can be searched for, commented on or reopened at any point. If you'd like a closed stale issue to be considered, feel free to either re-open the issue directly or contact a developer. To extend the lifetime of an issue please comment below, it helps us see that this is still affecting you and you want it fixed in the near-future. Extending the lifetime of an issue may cause the development team to prioritise it over other issues, which may be closed as stale instead.