1 ECE 3574: Applied Software Design Changwoo Min 2 Administrativia • Office Hours were decided! • See Canvas for details. 3 Meeting 2: version control • The goal of the next few meetings is to learn about programming tools other than the compiler and how to use representative versions of them. • Source Code Management (Version Control) • Source Code Configuration and Build • Testing Tools 4 Text manipulation • Plain text is the raw material of programming and the most stable digital form of storing knowledge. • You need to be adept at creating it, modifying it, searching it, and filtering it. • A key tool is your editor. • Pick a powerful one and learn how to use it effectively (e.g. keyboard shortcuts). • vim, emacs, atom, sublime text, etc. 5 Source code management • If you are copying source for backup, you are doing wrong • Source code management (SCM), also called version control • Keeps track of every change made to your code (and by whom). • It can act as an unlimited undo for your project • Documents what changes were made, by whom, and when • Provides archiving and reproducibility of software builds. • Always use some form of source code management, even for small projects. • We will be using git for this 6 Software configuration and build tools • You should be able to build all dependencies and the code itself, in debug and release mode, for all platforms supported in a single step. • This can be done by a variety of means, including customs scripts and IDE tooling. • We will be using a popular open source tool for this called cmake . 7 Testing and status • One of challenges in large-scale software development is to ensure keep working code working. • Frequent, automated test is crucial. • Untested Code is Broken Code • You should be able to also run the tests associated with a project in a single step. 8 Testing and status • This should be a regular part of the build process. • Examples: Catch, CxxTest, Google Test, CppUnit (and many more) • CMake includes a way to specify tests to run as part of the build process so we will use that. • We will spend an entire class meeting on this important topic in week three. This week we will look at the very basics using Catch . 9 Static checkers • Static typed languages like C++ allow a large class of bugs to be caught before the code is run. • Modern compilers provide a number of checks that can be applied, although external tools exist as well. • The compiler can generate warnings to prevent a large class of bugs. In particular code should compile cleanly with no warnings. • There are also tools like cppcheck and cpplint that can carry out specific checks. Teams often have their own per-projects scripts as well. • Example: Sparse for Linux kernel 10 Dynamic checkers • Once code is compiled and run it can also be checked for errors, usually by instrumenting the code automatically or at the run-time level. • This can be used to detect a wide variety of problems, notably memory mismanagement. • Examples: the valgrind suite of tools under unix and the VC++ leak detection facilities on Windows. 11 Code style checkers • C++ is a very large and complex language. It is often desirable to limit the parts of the language used. • Because code is read much more than it is compiled, uniform formatting and style rules are needed. • This applies to personal projects, where you might be reading you own code months (or years) after writing it, as well as multi-person projects. 12 Code style checkers • Each organization and project will have its own style guidelines as there is no one-true-style • Examples • Google C++ Style Guide • WebKit • LLVM • Fortunately many of the pedantic rules, where braces go, etc, can be fixed automatically. • Example tools: clang-format, Artistic Style 13 Code generators • Code generators are “code that writes code”, programs that output code, usually from some form of textual input. • These come in two forms, passive and active. • Passive generators are run only once and are appropriate for a few use cases, for example generating source files from templates or for generating lookup tables. • Active generators run each time the build is run. We will see an example of an active code generator from the QT library this semester, the Meta- Object Compiler, or moc . 14 Course tools In this course we will use just a few tools from those available • git for managing source code (command-line or GUI) • cmake for build configuration • Testing using Catch and Qt testing framework • code coverage and memory checkers 15 Version control: git • Git is a version control software • tracking changes in computer files • Initially developed by Linus Torvalds for development of the Linux kernel • Extensively using in many other software development • Github https://github.com/ is a git service provider • Distributed revision control system • Every git directory on every computer is a full-fledged repository with complete history 16 Essential git commands $ # 1. install and configure $ sudo dnf install git # sudo apt-get install git $ git config --global user.name "John Doe" # set your name and email for history $ git config --global user.email [email protected] $ # 2. creat a repository $ git init # create a new local repo $ git clone https://github.com/torvalds/linux.git # clone an existing repo $ # 3. tags $ git tag # list all existing tags $ git checkout v4.18 # checkout the tagged version $ # 4. commit history (or use tig for prettier output) $ git log # show all commit history $ git log <file> # show changes over time for a file $ git blame <file> # who changed what and when in <file> 17 Essential git commands $ # 5. local changes $ git status # show changed files $ git diff # show changed lines $ git add <file> # add <file> to the next commit $ git commit # commit previously staged files to my local repo $ # 6. publish and update $ git push # publish a committed local changes to a remote repo $ git pull # update a local repo 18 git workflow • Source: Pro Git 19 git workflow • Source: Pro Git 20 Git command cheat sheet init - initialize a new repository clone - clone an existing repository: local and remote status - see the state of your repository diff - examine details of what has changed add - adding changes to the index commit - commiting the changes in the index log - list previous changes push - pushing changes “upstream” tag - give your commits names • Useful git tutorials: Atlassian, Github, TutorialsPoint, Linux kernel • How to setup SSH for GitHub 21 Exercise 02: git • See Website • Don’t forget to upload git log screenshot to Canvas 22 Let’s talk about Project 1 • See Canvas 23 Next actions and reminders • Reading on VirtualBox and Vagrant 24 Further readings • The Linux tools that I am using… • vim: video, my vimrc • tmux: tutorial, video • git: video • cscope: tutorial • gdb: tutorial.