#+TITLE: Introduction to C++ Part II #+SUBTITLE: An IOP Student Organized Workshop #+AUTHOR: Rohit Goswami MInstP # I need the footnotes to be inlined #+STARTUP: fninline #+EXCLUDE_TAGS: noexport #+BEGIN_SRC emacs-lisp :exports none :eval always (require 'ox-extra) (ox-extras-activate '(ignore-headlines)) #+END_SRC * Configuration :ignoreheading:ignore: :PROPERTIES: :VISIBILITY: folded :END: # Kanged from https://gitlab.com/oer/oer-reveal/blob/master/org/config.org # Also https://gitlab.com/oer/emacs-reveal-howto/-/blob/master/howto.org ** General Options :ignoreheading:ignore: # No Table of contents, no section numbers #+OPTIONS: toc:nil num:t # Enable smart quotes #+OPTIONS: ':t ** RevealJS Options :ignoreheading:ignore: # Enable: browser history, slide numbers, fragment IDs in URLs, mouse wheel, links between presentations #+OPTIONS: reveal_history:t reveal_slide_number:t reveal_fragmentinurl:t #+OPTIONS: reveal_mousewheel:t reveal_inter_presentation_links:t # Disable separate PDF pages for each fragment. Just use one per slide. #+OPTIONS: reveal_pdfseparatefragments:nil # Display notes on separate page for PDF export. #+REVEAL_EXPORT_NOTES_TO_PDF: separate-page # Transition styles: none/fade/slide/convex/concave/zoom/cube #+REVEAL_TRANS: fade # Set a base theme, then override #+REVEAL_THEME: white #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.config/doom/revealExtras/robot-lung.css #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.config/doom/revealExtras/oerFragments.css #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.config/doom/revealExtras/rlExtras.css #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.config/doom/revealExtras/noImgBoxes.css #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.config/doom/revealExtras/moreCode.css #+REVEAL_MARGIN: 0.2 #+REVEAL_PREAMBLE:

#+REVEAL_PLUGINS: (notes search zoom) # The following variables are non-standard. # Do not display TOC-progress on title slide. #+REVEAL_TITLE_SLIDE_STATE: no-toc-progress # Do not display TOC-progress on TOC slide. #+REVEAL_TOC_SLIDE_STATE: no-toc-progress # Do not include TOC slide in TOC-progress. #+REVEAL_TOC_SLIDE_CLASS: no-toc-progress # Use different heading for TOC. #+REVEAL_TOC_SLIDE_TITLE: Agenda ** External Resources :ignoreheading:ignore: # Note that doom-emacs sets this variable # https://github.com/hlissner/doom-emacs/blob/develop/modules/lang/org/contrib/present.el #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.emacs.d/.local/straight/build-27.2/revealjs/plugin/accessibility/helper.css #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.emacs.d/.local/straight/build-27.2/revealjs/plugin/toc-progress/toc-progress.css #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.emacs.d/.local/straight/build-27.2/revealjs/dist/theme/toc-style.css #+REVEAL_EXTRA_CSS: /Users/rohitgoswami/.emacs.d/.local/straight/build-27.2/revealjs/dist/theme/fonts/source-sans-pro/source-sans-pro.css # Allow to selectively hide links. #+REVEAL_EXTRA_SCRIPTS: ("/Users/rohitgoswami/.emacs.d/.local/straight/build-27.2/revealjs/dist/theme/hidelinks.js") # The following creates an empty footer, for which the css style defines # a height that agrees with the TOC-progress footer’s height. # In this way, the footer’s height is taken into account by reveal.js’s # size calculations. #+REVEAL_SLIDE_FOOTER:
#+OPTIONS: reveal_toc_footer:t ** Macros :ignoreheading:ignore: # Set a default bib file. # Macros to display square brackets (in texts of hyperlinks). # Based on: https://emacs.stackexchange.com/questions/7792/can-i-make-links-in-org-mode-that-contain-brackets-or # Square Bracket Open [ #+MACRO: BO @@latex:\char91{}@@@@html:[@@ # Square Bracket Close ] #+MACRO: BC @@latex:\char93{}@@@@html:]@@ # Macro for forced line break, e.g., in titles. #+MACRO: BR @@latex:\\@@@@html:
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For LaTeX, output first attribute as is and # ignore second one. #+MACRO: abbr (eval (concat "@@latex:" Introduction to C++ Part II "@@@@html:" Introduction to C++ Part II "@@")) # Macros to display code in different colors. #+MACRO: blackcode (eval (format "@@html:%s@@ @@latex:\\verb|%s|@@" (org-html-encode-plain-text Introduction to C++ Part II) Introduction to C++ Part II)) #+MACRO: redcode (eval (format "@@html:%s@@ @@latex:\\rverb|%s|@@" (org-html-encode-plain-text Introduction to C++ Part II) Introduction to C++ Part II)) #+MACRO: greencode (eval (format "@@html:%s@@ @@latex:\\gverb|%s|@@" (org-html-encode-plain-text Introduction to C++ Part II) Introduction to C++ Part II)) #+MACRO: bluecode (eval (format "@@html:%s@@ @@latex:\\bverb|%s|@@" (org-html-encode-plain-text Introduction to C++ Part II) Introduction to C++ Part II)) ** LaTeX Options :ignoreheading:ignore: # Setup for PDF generation via LaTeX export. #+LATEX_CLASS_OPTIONS: [a4paper] #+LATEX_HEADER: \usepackage[backend=biber,style=alphabetic]{biblatex} #+LATEX_HEADER: \addbibresource{~/GDrive/zotLib.bib} #+LATEX_HEADER: \newenvironment{notes}{\par\footnotesize}{\par} #+LATEX_HEADER: \newenvironment{NOTES}{\par\footnotesize}{\par} #+LATEX_HEADER: \newenvironment{leftcol}{\begin{minipage}{.49\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{rightcol}{\begin{minipage}{.49\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{leftcol30}{\begin{minipage}{.29\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{leftcol40}{\begin{minipage}{.39\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{leftcol60}{\begin{minipage}{.59\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{leftcol70}{\begin{minipage}{.69\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{rightcol30}{\begin{minipage}{.29\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{rightcol40}{\begin{minipage}{.39\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{rightcol60}{\begin{minipage}{.59\textwidth}}{\end{minipage}} #+LATEX_HEADER: \newenvironment{rightcol70}{\begin{minipage}{.69\textwidth}}{\end{minipage}} #+LATEX_HEADER: \usepackage{newunicodechar} #+LATEX_HEADER: \newunicodechar{≈}{$\approx$} #+LATEX_HEADER: \newunicodechar{⋮}{\vdots} #+LATEX_HEADER: \newunicodechar{ }{~} #+LATEX_HEADER: \usepackage{xcolor} #+LATEX_HEADER: \definecolor{darkred}{rgb}{0.3, 0.0, 0.0} #+LATEX_HEADER: \definecolor{darkgreen}{rgb}{0.0, 0.3, 0.1} #+LATEX_HEADER: \definecolor{darkblue}{rgb}{0.0, 0.1, 0.3} #+LATEX_HEADER: \definecolor{darkorange}{rgb}{1.0, 0.55, 0.0} #+LATEX_HEADER: \definecolor{sienna}{rgb}{0.53, 0.18, 0.09} #+LATEX_HEADER: \hypersetup{colorlinks,linkcolor=darkblue,citecolor=darkblue,urlcolor=darkgreen} #+LATEX_HEADER: \usepackage{newverbs} #+LATEX_HEADER: \newverbcommand{\rverb}{\color{darkred}}{} #+LATEX_HEADER: \newverbcommand{\gverb}{\color{darkgreen}}{} #+LATEX_HEADER: \newverbcommand{\bverb}{\color{darkblue}}{} * Start Here :ignoreheading:ignore: * Brief Introduction ** Hello! - Find me here: https://rgoswami.me - Who? + *Rohit Goswami* MInstP - Doctoral Researcher, University of Iceland, Faculty of Physical Sciences #+begin_leftcol [[file:images/physUoI.png]] file:images/IOP-MasterLogo.png #+end_leftcol #+begin_rightcol file:images/rannisLogo.png #+DOWNLOADED: screenshot @ 2021-04-13 02:55:57 #+ATTR_HTML: :width 70% :height 70% [[file:images/Hello!/2021-04-13_02-55-57_screenshot.png]] #+end_rightcol # ** What I Do # #+begin_leftcol # file:images/stuff/volcano.png # #+end_leftcol # #+begin_rightcol # #+ATTR_REVEAL: :frag appear # - A good place to work on Water!! # file:images/collages/ice7.png # #+end_rightcol ** Logistics #+ATTR_REVEAL: :frag appear - All contents are [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2][hosted on GitHub]] + Slides are in ~docs/pres~ #+ATTR_REVEAL: :frag appear - Slides have shortned commit IDs + These lead to specific points in the ~git log~ #+ATTR_REVEAL: :frag appear - Questions are welcome after / during the lecture + [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/discussions/categories/q-a][GitHub Discussions]] have been set up for this * Local Project Layouts ** Language Agnostic Beginnings #+ATTR_REVEAL: :frag appear #+BEGIN_leftcol #+ATTR_REVEAL: :frag (appear) - ~Readme.{md,org}~ :: Motivation, rationale, license, installation instructions - ~LICENSE~ :: Plain text, and preferably an open license - [[https://github.com/azu/license-generator][license-generator]] is pretty handy for this - ~.gitignore~ :: Lists files which do not need to be committed; typically generated files - [[https://github.com/simonwhitaker/gibo][gibo]] can be used to generate these #+END_leftcol #+BEGIN_rightcol #+ATTR_REVEAL: :frag appear #+begin_src bash $ git init # Inside project $ gibo macOS Windows Xcode Emacs \ Vim Python C++ \ CMake TeX > .gitignore $ touch readme.md $ license-generator MIT \ --author "Person" $ tree -L 2 . ├── LICENSE ├── docs │ └── pres └── readme.org 2 directories, 2 files #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/9c294144a3d5518dfe03ad53912f2e768e6cc47e][9c29414]] #+end_gcid #+END_rightcol ** C++ Project Structure #+ATTR_REVEAL: :frag appear #+BEGIN_leftcol #+ATTR_REVEAL: :frag (appear) - ~src/~ :: Should be split into libraries and executables - ~include/~ :: For headers, internal and external - ~docs/~ :: Documentation of all kinds, typically including markdown files - ~CMakeLists.txt~ :: The project build system - ~ci/~ :: Scripts for continuous integration #+END_leftcol #+BEGIN_rightcol #+DOWNLOADED: screenshot @ 2021-04-12 21:03:39 #+ATTR_REVEAL: :frag appear [[file:images/C++_Project_Structure/2021-04-12_21-03-39_screenshot.png]] [fn:: Cute graphic [[http://archive.makzan.net/images/introducing-web-design/preprocessing.png][from here]]] #+ATTR_REVEAL: :frag appear #+begin_src cpp // Along each -I and INCLUDE #include #+end_src #+ATTR_REVEAL: :frag appear #+begin_src cpp // Starts in the same directory // Reverse order upward // -I and INCLUDE #include "path-spec" #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/a5a0a9ebac0340a5dc7c1c192e062f3a68d32cc4][a5a0a9e]] #+end_gcid #+END_rightcol * Iterative Improvements - I ** Refactoring CMakefile - I #+begin_leftcol - Comments are imperative - Segregation of build allows for easy cleanup - ~rm -rf build~ #+ATTR_REVEAL: :frag appear #+begin_src cmake # --- Variables if(NOT CMAKE_BUILD_TYPE) set(CMAKE_BUILD_TYPE Release endif() set(CMAKE_CXX_FLAGS "-Wall -Wextra") set(CMAKE_CXX_FLAGS_DEBUG "-g") set(CMAKE_CXX_FLAGS_RELEASE "-O3") #+end_src #+ATTR_REVEAL: :frag appear #+begin_src bash $ # Should fail!!! $ cmake . #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/8193ad90fe6755f6c39d66f175572556dbcad5ad][8193ad9]] #+end_gcid #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src cmake cmake_minimum_required(VERSION 3.14 FATAL_ERROR) # ---- Project ---- project( PenningTrapSimulationII VERSION 1.0 LANGUAGES CXX ) # ---- Include guards ---- if(PROJECT_SOURCE_DIR STREQUAL PROJECT_BINARY_DIR) message( FATAL_ERROR "In-source builds not allowed. Please make a new directory (called a build directory) and run CMake from there." ) endif() #+end_src #+ATTR_REVEAL: :frag appear #+begin_src bash $ # Works $ cmake -H. -Bbuild $ cmake --build build $ cd build $ simulation.exe #+end_src #+end_rightcol ** Header Only Includes #+begin_leftcol #+ATTR_REVEAL: :frag appear - These are meant for small classes + With inlined definitions #+ATTR_REVEAL: :frag appear #+begin_src cpp #ifndef IOP_VEC_H #define IOP_VEC_H ... #endif /* IOP_VEC_H */ #+end_src #+ATTR_REVEAL: :frag appear - Prevents multiple inclusion - Modularity means more unit-tests + Better guarantees #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src cmake # --- Library set(headers "${CMAKE_CURRENT_SOURCE_DIR}/include/math_types/iop_vec.hpp") set(sources "${CMAKE_CURRENT_SOURCE_DIR}/src/main.cpp") # Build add_executable(simulation.exe ${sources}) # Add to INCLUDE target_include_directories( simulation.exe PUBLIC $ ) #+end_src #+ATTR_REVEAL: :frag appear - We prefer ~<>~ to ~""~ for includes #+ATTR_REVEAL: :frag appear #+begin_src cpp #include #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/9ca7f3a123b9891159a805fe78b549a6762744da][9ca7f3a]] #+end_gcid #+end_rightcol ** Namespaces #+begin_leftcol #+ATTR_REVEAL: :frag appear - Further improves modularity + Fewer clashes + *Never* use ~using~ #+ATTR_REVEAL: :frag appear #+begin_src cpp namespace iopdat { // data_types/iop_particle.hpp class Particle { public: Vector3 position; ... } } #+end_src #+ATTR_REVEAL: :frag appear - Same conceptual region, even across files #+ATTR_REVEAL: :frag appear #+begin_src cpp namespace iopdat { // data_types/iop_vec.hpp class Vector3 { ... } } #+end_src #+end_leftcol #+begin_rightcol #+DOWNLOADED: screenshot @ 2021-04-12 23:21:01 #+ATTR_REVEAL: :frag appear [[file:images/Iterative_Improvements_-_I/2021-04-12_23-21-01_screenshot.png]] #+ATTR_REVEAL: :frag appear #+begin_src cmake set(headers "include/data_types/iop_vec.hpp" "include/data_types/iop_particle.hpp" ) #+end_src #+ATTR_REVEAL: :frag appear #+begin_src cpp #include #include #+end_src #+ATTR_REVEAL: :frag appear - Regrouped the ~data_types~ + ~math_types~ wasn't primitive enough + Refactoring early *is normal* - With _tests_ #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/2f1b16115cd612f2a3efd767dff4683a4f4657a9][2f1b161]] #+end_gcid #+end_rightcol ** Compiled Libraries #+begin_leftcol *Before* #+ATTR_REVEAL: :frag appear #+begin_src cpp class TimeStepper { private: std::vector physics_list; iopdat::Particle p; double dt; public: TimeStepper(double time_step_size, double charge, double mass) : p(charge, mass) { dt = time_step_size; } ... }; #+end_src #+end_leftcol #+begin_rightcol *After* #+ATTR_REVEAL: :frag appear #+begin_src cpp class TimeStepper { private: std::vector physics_list; iopdat::Particle p; double dt; public: TimeStepper(double time_step_size, double charge, double mass); void AddProcess(PhysicsProcess* process); void Setup(iopdat::Vector3 position, iopdat::Vector3 Velocity); void Step(); void Print(); }; #+end_src #+end_rightcol *** Why? #+begin_leftcol *Header Only* #+ATTR_REVEAL: :frag appear - Easier to install #+ATTR_REVEAL: :frag appear - Can be dropped in and versioned #+ATTR_REVEAL: :frag appear - Slow, especially installed + They are expanded *Compiled* #+ATTR_REVEAL: :frag appear - Compiled code is faster #+ATTR_REVEAL: :frag appear - Adds complexity though + Needs a build system #+ATTR_REVEAL: :frag appear - Can easier to read + More modular + Easier to document #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src bash $ tree -L . . ├── CMakeLists.txt ├── LICENSE ├── docs │ └── pres ├── include │ ├── data_types │ └── phys_procs.hpp ├── libsrc │ └── phys_procs.cpp ├── readme.org └── src ├── CMakeLists.txt └── main.cpp 6 directories, 7 files #+end_src #+end_rightcol *** How? - I Code Separation #+begin_leftcol #+ATTR_REVEAL: :frag appear - *declared* in ~.hpp~ #+ATTR_REVEAL: :frag appear #+begin_src cpp /** * @brief Takes a step * @returns None. */ void Step(); #+end_src #+ATTR_REVEAL: :frag appear - The build system takes on most of the debt + Compiles the code as a library - "header-only" libraries can also be built - Ensures it can be linked at runtime #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear - *defined* in ~.cpp~ #+ATTR_REVEAL: :frag appear #+begin_src cpp /** * @detail The algorithm is a direct interpretation * of standard mechanics */ void physproc::TimeStepper::Step() { iopdat::Vector3 F(0, 0, 0); for (int i = 0; i < physics_list.size(); i++) { F += physics_list.at(i)->Force(p); } iopdat::Vector3 dv(dt * F.x / p.mass, dt * F.y / p.mass, dt * F.z / p.mass); p.velocity += dv; p.position += iopdat::Vector3(p.velocity.x * dt, p.velocity.y * dt, p.velocity.z * dt); } #+end_src #+end_rightcol *** How? - II Building and Linking #+begin_leftcol #+ATTR_REVEAL: :frag appear - For *header-only* libraries + PUBLIC -> INTERFACE - target: + ~add_library(ioplib INTERFACE)~ #+ATTR_REVEAL: :frag appear #+begin_src cpp // main.cpp ... #include #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/e6d048e88c103df18e9bde45416299d0801aa427][e6d048e]] #+end_gcid #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src cmake # Build order add_dependencies(simulation.exe ioplib) # Libraries target_link_libraries(simulation.exe ioplib) # Dependencies add_library( ioplib SHARED "libsrc/phys_procs.cpp" ) # Still need the older headers target_include_directories( ioplib PUBLIC $ ) #+end_src #+end_rightcol *** When? #+ATTR_REVEAL: :frag appear - Larger projects refactor often #+ATTR_REVEAL: :frag appear - Modular components make it easy for new contributors #+ATTR_REVEAL: :frag appear - Reuse of code is easier this way #+ATTR_REVEAL: :frag appear - The speed benefits can be considerable + Speed here means compilation time #+ATTR_REVEAL: :frag appear - ~boost~ is a classic example of a mostly compiled library #+ATTR_REVEAL: :frag appear - ~Eigen3~ is famously header-only #+ATTR_REVEAL: :frag appear #+begin_quote Let there be libraries!! --- Rohit Goswami (2021) #+end_quote * Package Management ** Current Scenario #+begin_leftcol #+ATTR_REVEAL: :frag appear file:images/xkcd/python_xkcd.png [fn:: Comic [[https://xkcd.com/353/][from here]]] #+ATTR_REVEAL: :frag appear - *Nix is the answer!!* (not here) #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear - ~Python~ :: ~poetry~, ~pipenv~, ~pyenv~ - ~C++~ :: ~conan~, ~vcpkg~, _~cpm~_ #+ATTR_REVEAL: :frag appear file:images/collages/systemManagers.png #+end_rightcol ** CPM and CMake #+ATTR_REVEAL: :frag appear #+begin_src bash mkdir -p cmake wget -O cmake/CPM.cmake "https://github.com/cpm-cmake/\ CPM.cmake/releases/latest/download/get_cpm.cmake" # Can get slow otherwise, rebuilds constantly export CPM_SOURCE_CACHE=$HOME/.cache/CPM #+end_src #+ATTR_REVEAL: :frag appear #+begin_src cmake # --- Helpers include(cmake/CPM.cmake) CPMUsePackageLock(package-lock.cmake) #+end_src #+ATTR_REVEAL: :frag appear #+begin_src bash # We like locks cmake -H. -Bbuild cmake --build build --target cpm-update-package-lock #+end_src * Testing and Continuous Integration ** Testing Frameworks #+begin_leftcol #+ATTR_REVEAL: :frag appear - ~C++~ has great testing frameworks + _~Catch2~_, ~googletest~, ~doctest~, etc. #+ATTR_REVEAL: :frag appear - *Unit tests* are the first layer + Ensure each function outputs as expected #+ATTR_REVEAL: :frag appear - *Integration tests* are for workflows + Ensure each series of tasks connect correctly #+ATTR_REVEAL: :frag appear #+begin_src cmake # Catch2 CMakeLists.txt include(CTest) add_subdirectory(tests) enable_testing() #+end_src #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src cmake # --- Externals ./tests/CMakeLists.txt include(../cmake/CPM.cmake) CPMAddPackage("gh:catchorg/Catch2@2.13.4") add_executable(particle_tests main.cpp vector_particle-test.cpp phys_processes-test.cpp ) # Link everything target_link_libraries(particle_tests ioplib Catch2) target_compile_features(particle_tests PRIVATE cxx_std_17) # Project Libraries include_directories( ../src/include/data_types ${PROJECT_SOURCE_DIR}/src/include/) # ---- Run tests ---- add_test(NAME particleIOP-unit-tests COMMAND $) #+end_src #+end_rightcol ** Writing Tests #+begin_leftcol #+ATTR_REVEAL: :frag appear #+begin_src cpp #define CATCH_CONFIG_MAIN #define CATCH_CONFIG_RUNNER #include #+end_src #+ATTR_REVEAL: :frag appear - The macros must not be repeated #+ATTR_REVEAL: :frag appear - Many more test scenarios + d-SEAMS [[https://github.com/d-SEAMS/seams-core][has examples]] + [[https://github.com/catchorg/Catch2/blob/devel/docs/tutorial.md#scaling-up][Official docs are great]] #+ATTR_REVEAL: :frag appear - Try *fixing gravity* as _homework_! + Open a PR (pull request) when done #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src cpp #include #include #include #include #include TEST_CASE("Basic Vector class tests", "Vector3") { iopdat::Vector3 a{1, 2, 3}; REQUIRE(sizeof(a) == 24); REQUIRE(sizeof(a) / sizeof(1) == 6); REQUIRE(sizeof(a) / sizeof(1.0) == 3); iopdat::Vector3 b{4, 5, 6}; b += a; REQUIRE(b.x == 5); REQUIRE(b.y == 7); REQUIRE(b.z == 9); std::cout << b.x; } #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/d9ded32c144fde02667dde19f70cf49a11bd5625][d9ded32]] #+end_gcid #+end_rightcol ** Continuous Integration #+ATTR_REVEAL: :frag appear - No one likes switching computers to test + MacOS, Windows (WSL often), Many Linux distributions #+ATTR_REVEAL: :frag appear - Some tests run for a long time + Less attractive locally - ~nixpkgs~ can take over a day! #+ATTR_REVEAL: :frag appear - There are far too many options nowadays + Wercker, +Travis CI+, Shippable, GitLab CI, _Github Actions_ #+ATTR_REVEAL: :frag appear - Mostly transient ~docker~ or ~nix~ based systems + Setup can be annoying without ~nix~ ** Github Actions #+begin_leftcol #+ATTR_REVEAL: :frag appear - [[https://github.com/nektos/act#installation][act allows]] local tests #+ATTR_REVEAL: :frag appear #+begin_src yaml name: CMake on: [push] env: BUILD_TYPE: Release jobs: build: runs-on: ${{ matrix.OS }} name: "${{ matrix.BUILD_TYPE }}" strategy: matrix: include: - BUILD_TYPE: Debug OS: ubuntu-latest - BUILD_TYPE: Debug OS: macos-latest - BUILD_TYPE: Debug ARCH: x86_64 OS: windows-latest # broken #+end_src #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src yaml steps: - uses: actions/checkout@v2 - name: Create Build Environment run: cmake -E make_directory ${{github.workspace}}/build - name: Configure CMake shell: bash working-directory: ${{github.workspace}}/build run: cmake $GITHUB_WORKSPACE -DCMAKE_BUILD_TYPE=$BUILD_TYPE - name: Build working-directory: ${{github.workspace}}/build shell: bash run: cmake --build . --config $BUILD_TYPE - name: Test working-directory: ${{github.workspace}}/build shell: bash run: ctest -C $BUILD_TYPE #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/1293af3c860f29646d49339c1e50d37267a03f9b][1293af3]] #+end_gcid #+end_rightcol * Embedding and Mixed Compilation ** Why Embed? *** Visuals?? #+ATTR_REVEAL: :frag appear - File I/O is sufficient #+ATTR_REVEAL: :frag appear #+begin_src bash simulate.exe > someFile.txt #+end_src #+ATTR_REVEAL: :frag appear #+begin_src python import numpy as np import matplotlib.pyplot as plt import matplotlib.animation as animation import pandas as pd df = pd.read_csv("someFile.txt", sep=" ") # Do stuff now #+end_src #+ATTR_REVEAL: :frag appear - Can be better for HPC systems + *Why embed / interpolate?* ** Better Examples *** d-SEAMS - Uses ~lua~ to expose a scripting engine + Computation is still ~C++~ - Reduces compilation requirements + Increases flexibility fullcite:goswamiDSEAMSDeferredStructural2020 #+DOWNLOADED: screenshot @ 2021-04-13 03:36:06 [[file:images/Better_Examples/2021-04-13_03-36-06_screenshot.png]] *** EON - EON uses a server client architecture - Is meant for distributed use fullcite:henkelmanLongTimeScale2001 #+DOWNLOADED: screenshot @ 2021-04-13 03:39:23 #+ATTR_HTML: :width 80% :height 80% [[file:images/Better_Examples/2021-04-13_03-39-23_screenshot.png]] * PyBind11 ** Embedding Python #+begin_leftcol #+ATTR_REVEAL: :frag appear - Example adapted [[https://github.com/tttapa/Pybind11-Matplotlib-Cpp][from here]] #+ATTR_REVEAL: :frag appear #+begin_src bash pip install matplotlib #+end_src #+ATTR_REVEAL: :frag appear #+begin_src cmake CPMAddPackage( NAME pybind11 GITHUB_REPOSITORY pybind/pybind11 GIT_TAG v2.6.1 ) target_link_libraries(simulation.exe ioplib pybind11::embed) #+end_src #+ATTR_REVEAL: :frag appear #+begin_src cpp // py::scoped_interpreter #include #include namespace py = pybind11; int main() { std::vector signal(1024); for (size_t i = 0; i < signal.size(); ++i) signal[i] = std::exp(i / -256.0) * std::cos(2 * M_PI * 8 * i / 1024.0); #+end_src #+end_leftcol #+begin_rightcol #+ATTR_REVEAL: :frag appear #+begin_src cpp py::scoped_interpreter guard{}; using namespace py::literals; // Save the necessary local variables // in a Python dict py::dict locals = py::dict{ "signal"_a = signal, }; // Execute Python code, using the variables // saved in `locals` py::exec(R"( import matplotlib.pyplot as plt plt.plot(signal) plt.show() )", py::globals(), locals); } #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/5c21716f31f1498ba9e67166ad6faba4cb9159af][5c21716]] #+end_gcid #+end_rightcol *** Sample Run #+DOWNLOADED: screenshot @ 2021-04-13 04:08:12 [[file:images/Embedding_Python/2021-04-13_04-08-12_screenshot.png]] ** Proton Stepper #+begin_leftcol #+ATTR_REVEAL: :frag appear #+begin_src cpp // Getters double physproc::TimeStepper::getX() { return p.position.x; } #+end_src #+ATTR_REVEAL: :frag appear #+begin_src cpp // Accumulators std::vector x, y, z; for (int i = 0; i < 1E3; i++) { ProtonStepper.Step(); if (i % 7 == 0) { x.push_back(ProtonStepper.getX()); ... } } py::scoped_interpreter guard{}; using namespace py::literals; py::dict locals = py::dict{ "x"_a = x, ... }; py::exec(R"( )", py::globals(), locals); #+end_src #+begin_gcid [[https://github.com/HaoZeke/2021_April_IOP_IntroductionToCpp_Part2/commit/59555bce6a02ffe57bbd3e7ceefa5f8b271c4568][59555bc]] #+end_gcid #+end_leftcol #+begin_rightcol #+DOWNLOADED: screenshot @ 2021-04-13 04:37:30 #+ATTR_REVEAL: :frag appear [[file:images/Proton_Stepper/2021-04-13_04-37-30_screenshot.png]] #+ATTR_REVEAL: :frag appear #+begin_src python from mpl_toolkits.mplot3d import Axes3D import matplotlib.pyplot as plt fig = plt.figure() ax = fig.add_subplot(111, projection='3d') ax.scatter(x, y, z, c='r', marker='o') plt.show() #+end_src #+end_rightcol * Conclusions ** Omitted Topics #+ATTR_REVEAL: :frag appear - Documentation :: Possibly the most underrated skill in compuational work #+ATTR_REVEAL: :frag appear - Package Management :: Managing OS's #+ATTR_REVEAL: :frag appear - HPC and Parallelism :: Efficient data usage and algorithms #+ATTR_REVEAL: :frag appear - Code Review Practices :: Scrum and teamwork #+ATTR_REVEAL: :frag appear - Inter process communication :: Across networks and process, including serialization ** Further Resources - [[https://changkun.de/modern-cpp/en-us/00-preface/][Modern C++ Tutorial]] :: Community maintained, discusses features from C++11 onwards, spearheaded by Changkun Ou - [[http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines][C++ Core Guidelines]] :: Maintained by Bjarne and Herb, great to get the pulse of the community - [[https://docs.microsoft.com/en-us/cpp/cpp/welcome-back-to-cpp-modern-cpp?view=msvc-160][Microsoft Visual Studio]] :: Has a surprisingly good introduction and [[https://docs.microsoft.com/en-us/cpp/get-started/tutorial-console-cpp?view=msvc-160][even some projects]] - [[https://rgoswami.me/posts/ccon-tut-nix/][A Tutorial Introduction to Nix]] :: Package management at the system level in a reproducible manner - [[https://rgoswami.me/posts/symengine-gsod20/][SymEngine and the Season of Docs]] :: Describes the present SOTA for documentation practices in the context of a large multi-language project - [[https://www.jetbrains.com/help/clion/unit-testing-tutorial.html][CLion]] :: Has a solid tutorial on tests and frameworks in general * The End ** Bibliography :PROPERTIES: :CUSTOM_ID: bibliography :END: printbibliography:/Users/rohitgoswami/GDrive/zotLib.bib ** Thanks! :PROPERTIES: :reveal_background: #005ab6 :END: # Local Variables: # indent-tabs-mode: nil # org-src-preserve-indentation: t # End: