.. include:: C++: A One-Day Overview (2024-11-19 - 2024-11-21) ================================================= .. toctree:: :hidden: agenda .. sidebar:: **Github Repository** * https://github.com/jfasch/2024-11-19 **Original Agenda** * :doc:`agenda` **Material** * :doc:`/trainings/material/soup/cxx11/010-introduction/overview-livehacking-oo` This was unusual: a one-day course based on :doc:`/trainings/material/soup/cxx11/010-introduction/overview-livehacking-oo`, given three times in a row [#groundhog-day]_, to three different groups at the same company. The day was woven around :doc:`the screenplay `, which I used to live-hack `2024-11-19/intro.cpp `__ - which is the final outcome. See :doc:`the screenplay ` to see how we got there. Any deviations (asked questions, discussions) are documented below. .. contents:: :local: Course Flow: Questions And Discussions -------------------------------------- The following chapters correspond to sections in :doc:`/trainings/material/soup/cxx11/010-introduction/overview-livehacking-oo`, which are referred to in their respective sidebars. ``std::map``, And Pitfalls (:ref:`cxx11-overview-class-item-encap`) ................................................................... .. sidebar:: Section(s) in script * :ref:`cxx11-overview-class-item-encap` * :ref:`cxx11-overview-class-item-encap-pitfall` .. sidebar:: See also * :doc:`/trainings/material/soup/cxx03/060-stl/050-associative-containers/map` * :doc:`/trainings/material/soup/cxx03/060-stl/050-associative-containers/map-insert` * :ref:`cxx_map_inserting` ``std::map``, when filled using ``tdl["something"] = Item("... blah ...")``, requires ``class Item`` to have a default constructor. This is not entirely obvious, to say the least. **Problem**: ``std::map::operator[]()`` creates a node with a default-constructed value, which is then overwritten with ``Item("... blah ...")``. **Solution**: use ``std::map::insert()``, or even better in our case at least, use an initializer list and a ``const todo_list`` object. Demo of the pitfall (``std::map::operator[]()``) in `2024-11-19/map-pitfall-no1.cpp `__ Brace Initialization .................... .. sidebar:: Section(s) in script * :ref:`cxx11-overview-brace-init` .. sidebar:: See also * :doc:`/trainings/material/soup/cxx11/020-new-language-features/030-brace-initialization/group` Discussed the differences between ``{}`` and ``()``. See `2024-11-19/brace-init.cpp `__ Smart Pointers, And Move Semantics .................................. .. sidebar:: Section(s) in script * :ref:`cxx11-overview-smart-pointers` * :ref:`cxx11-overview-unique-ptr` * :ref:`cxx11-overview-move` * :ref:`cxx11-overview-shared-ptr` .. sidebar:: See also **Pointer Classes** * :doc:`/trainings/material/soup/cxx11/030-smart-pointers/introduction` * :doc:`/trainings/material/soup/cxx11/030-smart-pointers/uniqueptr` * :doc:`/trainings/material/soup/cxx11/030-smart-pointers/sharedptr` * (Not covered) :doc:`/trainings/material/soup/cxx11/030-smart-pointers/weakptr` * :doc:`/trainings/material/soup/cxx11/030-smart-pointers/040-closing-words/topic` **Move semantics, and Rvalue references** * :doc:`/trainings/material/soup/cxx11/020-new-language-features/060-move/overview` * :doc:`/trainings/material/soup/cxx11/020-new-language-features/060-move/livehack-string-move` * :doc:`/trainings/material/soup/cxx11/020-new-language-features/060-move/livehack-using-string-move` * :doc:`/trainings/material/soup/cxx11/020-new-language-features/060-move/afterword` While using ``std::shared_ptr<>`` in `2024-11-19/intro.cpp `__, we approached the topic in * `2024-11-19/shared-ptr-memory-mgmt.cpp `__ * `2024-11-19/unique-ptr-memory-mgmt.cpp `__ While we were at it, we discussed related topics like * Return value optimization (RVO) and `Copy Elision `__. Demo code in `2024-11-19/rvo-or-not.cpp `__ * Moving and rvalue references in general (:doc:`/trainings/material/soup/cxx11/020-new-language-features/060-move/group`) * Dual implementation (move and copy) of, say, ``std::vector::push_back()``. Demo code in `2024-11-19/push-back-move.cpp `__ Lambda ...... .. sidebar:: Section(s) in script * :ref:`cxx11-overview-lambda` * :ref:`cxx11-overview-lambda-todolist` .. sidebar:: See also * :doc:`/trainings/material/soup/cxx11/020-new-language-features/lambda/lambda` * :doc:`/trainings/material/soup/cxx11/020-new-language-features/lambda/lambda-is-functor` * :doc:`/trainings/material/soup/cxx11/020-new-language-features/lambda/lambda-is-functor-pitfall` * :doc:`/trainings/material/soup/cxx11/020-new-language-features/lambda/lambda-capture` * :doc:`/trainings/material/soup/cxx03/060-stl/020-algorithm/sort` Transformed `2024-11-19/intro.cpp `__ into something that is more to the point. Talk about interfaces, the cost of ``virtual`` (RTTI is not free), and readability in general. For what a lambda really is, see the old school functor demo (`2024-11-19/functor.cpp `__). Use cases for lambda: * The optional third parameter, ``Compare``, to ``std::sort`` (see `2024-11-19/sort-lambda.cpp `__) * Creating threads, and more specifically, using `std::async `__ (see `2024-11-19/async.cpp `__) .. rubric:: Footnotes .. [#groundhog-day] It went somewhat like the movie `Groundhog Day `__