sml
C++ Format
sml | C++ Format | |
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23 | 161 | |
1,081 | 19,350 | |
2.3% | 1.0% | |
6.8 | 9.7 | |
about 1 month ago | 4 days ago | |
C++ | C++ | |
Boost Software License 1.0 | GNU General Public License v3.0 or later |
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For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
sml
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Sharing Saturday #496
Anyway the need is not complicated, I need both entry and exit functions from every state, optionally allowing these functions to be coroutines (that's special sauce but for later), and an explicit state transition table which also have a way to say that a state can be accessed at any point. Also allow states to be state machines, optional FSM hierarchies. If you ignore the coroutine stuff it's pretty standard features these days, except that - Boost.MSM is quite archaic now (it was so novel when it was first released...) although it allows most of the features I talked about, I just think it will complicate my code unneecessarilly; - Boost-Ext.SML (not Boost) is almost perfect except it doesnt have entry/exit functions on states for some reason. Also last time we (as in in livestream) tried it in prototypes it didnt compile on msvc XD - Boost-Ext.SML2 is even better but still doesnt have entry/exit functions although it's in the plans.
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State machines with C++20 coroutines and Asio/Boost Async
Hello all. Being a huge fan of state machine and coroutines, I have been browsing around for examples of what other people do combine these two. I have been using boost-ext/sml for quite many projects and are quite happy about that. But when transitioning to code that relies on coroutines, I would like to write entry/exit/actions/guard methods that uses coroutines and where I can co_await on awaitables from Asio and more recently "Boost Async".
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Looking for well written, modern C++ (17/20) example projects for microcontrollers
boost-ext/sml: quite modern way of doing state machines using a DSL
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When Debug Symbols Get Large
I recently was troubleshooting a crash that backtraced through the boost::sml library [0]. The crash didn't actually have anything to do with the library, but it was used as the core event loop.
The backtrace -- as in, just the output from running `bt` in GDB -- was over a thousand wrapped lines long. There were ~5 stack frames that took up 200 lines of console each to print just the function name. That product's debug builds recently hit the 2GB line, which is enough that old versions of binutils complain.
I don't know what the solution is. There's some really neat stuff you can do with template metaprogramming, and in stripped release builds it compiles down extremely tiny. Plus the code is very clean to read. But it does feel like there isn't any kind of central vision for the C++ debugging experience, and bad interactions between highly-complex modern C++ typing, the compiler, and the debugger are probably only going to get worse unless somebody (the ISO committee? Vendors?) thinks really hard about debugging support.
[0]: https://github.com/boost-ext/sml
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[Boost::MSM] Huge Memory Usage Issue During Compilation
I'm a big fan of MSM but what you're experiencing is pretty normal for template-heavy libraries built on C++03 machinery (emulation of variadic templates is the usual culprit). It's probably not the answer you're hoping for, but the real solution is to switch to a library with more modern foundations. (I've been happily using [Boost::ext].SML for a few years but I'm reluctant to strongly recommend anything in particular since I haven't re-explored the problem space since I found it.)
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State machine suggestion?
The Boost one that you mention, seems to be one that it's kinda old. A "successor" of sorts is Boost SML. I've not used it yet, but certainly the first impressions are very good.
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Specifications for an open source finite state machine library
Or Boost.Sml
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Facts about State Machines
At our company, we rely a lot on https://github.com/boost-ext/sml
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What are some cool modern libraries you enjoy using?
I'm a big fan of boost::sml for representing state machines.
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[C++20] New way of meta-programming?
https://github.com/boost-ext/sml (State Machine DSL and backend for perfomance)
C++ Format
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C++ left arrow operator (2016)
Continuation passing monads form the basis of a perfectly valid and usable software architecture and programming pattern.
In the case of ostream and operator<<, this pattern reduces the number of intermediate objects that would otherwise be constructed.
If you object to iostream on religious or stylistic grounds, there's always fmt which is more like Go or Python string interpolation.[0]
0. https://fmt.dev
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C++ Game Utility Libraries: for Game Dev Rustaceans
GitHub repo: fmtlib/fmt
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Creating k-NN with C++ (from Scratch)
cmake_minimum_required(VERSION 3.5) project(knn_cpp CXX) # Set up C++ version and properties include(CheckIncludeFileCXX) check_include_file_cxx(any HAS_ANY) check_include_file_cxx(string_view HAS_STRING_VIEW) check_include_file_cxx(coroutine HAS_COROUTINE) set(CMAKE_CXX_STANDARD 20) set(CMAKE_BUILD_TYPE Debug) set(CMAKE_CXX_STANDARD_REQUIRED ON) set(CMAKE_CXX_EXTENSIONS OFF) # Copy data file to build directory file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/iris.data DESTINATION ${CMAKE_CURRENT_BINARY_DIR}) # Download library usinng FetchContent include(FetchContent) FetchContent_Declare(matplotplusplus GIT_REPOSITORY https://github.com/alandefreitas/matplotplusplus GIT_TAG origin/master) FetchContent_GetProperties(matplotplusplus) if(NOT matplotplusplus_POPULATED) FetchContent_Populate(matplotplusplus) add_subdirectory(${matplotplusplus_SOURCE_DIR} ${matplotplusplus_BINARY_DIR} EXCLUDE_FROM_ALL) endif() FetchContent_Declare( fmt GIT_REPOSITORY https://github.com/fmtlib/fmt.git GIT_TAG 7.1.3 # Adjust the version as needed ) FetchContent_MakeAvailable(fmt) # Add executable and link project libraries and folders add_executable(${PROJECT_NAME} main.cc) target_link_libraries(${PROJECT_NAME} PUBLIC matplot fmt::fmt) aux_source_directory(lib LIB_SRC) target_include_directories(${PROJECT_NAME} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}) target_sources(${PROJECT_NAME} PRIVATE ${LIB_SRC}) add_subdirectory(tests)
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Optimizing the unoptimizable: a journey to faster C++ compile times
Good catch, thanks! Fixed now. This explains why the difference was kinda low compared to another benchmark: https://github.com/fmtlib/fmt?tab=readme-ov-file#compile-tim....
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Learn Modern C++
> This is from C++23, right?
std::println is, yes.
> I wonder how available this is within compilers
https://en.cppreference.com/w/cpp/compiler_support says clang, gcc, and msvc all support it, though I don't know how recent those versions are off the top of my head.
In my understanding, with this specific feature, if you want a polyfill for older compilers, or to use some more cutting-edge features that haven't been standardized yet, https://github.com/fmtlib/fmt is available to you.
- The C++20 Naughty and Nice List for Game Devs
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For processing strings, streams in C++ can be slow
{fmt} has internal buffering but it's not yet exposed to users. There is a feature request for it: https://github.com/fmtlib/fmt/issues/2354. FILE buffering is not too bad but it can be easily optimized: https://www.zverovich.net/2020/08/04/optimal-file-buffer-siz....
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adoption of fmt based logging
Automatic use of operator<< when that exists was present in fmt until version 9.0.0. In version 9 you could use FMT_DEPRECATED_OSTREAM to opt in the old behaviour, but this too was removed in version 10.0.0. Now there is no way to automatically use operator<<.
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What's your favorite c++20 feature that should've been there 10 years ago?
You can install it https://github.com/fmtlib/fmt
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Codebases to read
Additionally, if you like low level stuff, check out libfmt (https://github.com/fmtlib/fmt) - not a big project, not difficult to understand. Or something like simdjson (https://github.com/simdjson/simdjson).
What are some alternatives?
hsm - Finite state machine library based on the boost hana meta programming library. It follows the principles of the boost msm and boost sml libraries, but tries to reduce own complex meta programming code to a minimum.
spdlog - Fast C++ logging library.
stm32plus - The C++ library for the STM32 F0, F100, F103, F107 and F4 microcontrollers
Better Enums - C++ compile-time enum to string, iteration, in a single header file
hana - Your standard library for metaprogramming
ZXing - ZXing ("Zebra Crossing") barcode scanning library for Java, Android
HFSM2 - High-Performance Hierarchical Finite State Machine Framework
FastFormat - The fastest, most robust C++ formatting library
Experimental Boost.DI - C++14 Dependency Injection Library
ZBar - Clone of the mercurial repository http://zbar.hg.sourceforge.net:8000/hgroot/zbar/zbar
Boost.Beast - HTTP and WebSocket built on Boost.Asio in C++11
Scintilla