Jonathan Müller @foonathan Twitter profile

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@Markiemaestro

Jonathan Müller

@foonathan

4 years

"How can I detect which C++ compiler is used?" "Oh, that's easy:" (via )

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Jonathan Müller

@foonathan

2 years

I'm currently optimizing lexy's JSON parser example. I've now reached a point where it is 12000% faster than all other JSON libraries. The trick is to consider all characters whitespace and skip them...

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Jonathan Müller

@foonathan

7 years

"Family name contains invalid characters." - No, my family name does not contain invalid characters by definition. Your program just sucks.

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Jonathan Müller

@foonathan

2 years

To countless people in the reddit comment section: No, somebody implementing their own language after they've failed to change an existing one, isn't throwing a tantrum. Programming languages are tools. If they don't work for you, switch. If no alternative exists, invent one.

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Jonathan Müller

@foonathan

2 years

New blog post: malloc() and free() are a bad API #cpp #cplusplus

malloc() and free() are a bad API

If you need to allocate dynamic memory in C, you use malloc() and free(). The API is very old, and while you might want to switch to a different implementation, be it jemalloc, tcmalloc, or mimalloc,...

www.foonathan.net

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Jonathan Müller

@foonathan

1 year

C++ optimization in a nutshell: #cpp #cplusplus

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Jonathan Müller

@foonathan

3 years

New blog post: I wrote a compile-time Brainfuck compiler that generates optimized assembly. The best part: I didn't need to do anything, I've tricked clang into doing it for me. Technique: Compile Time Code Generation and Optimization #cpp #cplusplus

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Jonathan Müller

@foonathan

2 years

I love reddit sometimes.

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Jonathan Müller

@foonathan

3 years

"We have strlen() to get the length of a string, strcpy() to copy a string, and strcmp() to compare a string. How should we call the function to search inside a string?" "Eh, I don't know. str..., str..." "Perfect, thanks!"

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Jonathan Müller

@foonathan

4 years

I have written a new library! lexy: a C++ parser combinator library #cpp #cplusplus

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Jonathan Müller

@foonathan

11 months

The "fun" thing about C++ is that static_cast<decltype((x))>(x) is a no-op, but static_cast<decltype(x)>(x) isn't.

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Jonathan Müller

@foonathan

2 years

UB is fun: Credit to u/geekfolk. #cpp #cplusplus

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Jonathan Müller

@foonathan

1 year

My day so far.

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Jonathan Müller

@foonathan

1 year

To improve my personal development experience I will at some point in my life write 1. My own programming language. 2. My own text editor/IDE. 3. My own OS and/or window manager. The question is: in what order?

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Jonathan Müller

@foonathan

6 years

My @meetingcpp "Writing Cache-Friendly C++" is online: Slides and further resources here: #cpp #cplusplus

Writing cache friendly C++ - Jonathan Müller - Meeting C++ 2018

Writing cache friendly C++Jonathan MüllerMeeting C++ 2018Slides: https://meetingcpp.com/mcpp/slides/

www.youtube.com

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Jonathan Müller

@foonathan

1 year

Shoutout to MSVC for ignoring [[no_unique_address]] and forcing you to use [[msvc::no_unique_address]] instead. That's exactly the point of standardized attributes.

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Jonathan Müller

@foonathan

6 years

Else if? Boring. I present to you: The else switch.

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Jonathan Müller

@foonathan

2 years

I have just released the first non-beta version of lexy. Want to parse anything in C++? Try it out. It has Unicode support, automatic error recovery, and many more features. #cpp #cplusplus

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Jonathan Müller

@foonathan

4 months

You can't debug modern C++ anymore because of all the std:: invoke.

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Jonathan Müller

@foonathan

2 years

@vzverovich 1. Strict aliasing violations. 2. Union type punning,. 3. std:vector 4. mmap 5. arbitrary pointer subtraction 6. treating raw memory as objects 7. signed integer overflow 8. function pointer casts And that's just my current project!

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Jonathan Müller

@foonathan

1 year

High-speed train to the airport is powered by Microsoft DOS.

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Jonathan Müller

@foonathan

2 years

@jntrnr The `else switch` when you don't have pattern matching:

Jonathan Müller

@foonathan

6 years

Else if? Boring. I present to you: The else switch.

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Jonathan Müller

@foonathan

1 year

How do Java people live with the net/foonathan/tweet/punchline/deeply_nested_folder/structure.java?! Isn't that really annoying to work with?

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Jonathan Müller

@foonathan

3 years

I've spent the last half hour looking for the bug in my coroutine related code for my upcoming @ACCUConf talk. Turns out, it was this for loop: for (auto i = 0; i != steps; ++steps)

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Jonathan Müller

@foonathan

6 years

Slides and additional resources of my #meetingcpp "Writing Cache-Friendly C++" are now available: #cpp #cplusplus

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Jonathan Müller

@foonathan

3 years

r/cpp post about the latest CppCast episode. Title: "Beautiful C++" Contents: 195 comment discussion about Rust. Ah, reddit, never change.

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Jonathan Müller

@foonathan

2 years

std::deque seems to be an underrated container: * you can efficiently insert at the front * the elements have pointer stability * reallocation doesn't require copying things around Sure, pure iteration is slower as it's a collection of segmented array - am I missing sth else?

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Jonathan Müller

@foonathan

3 years

The lifecycle of a C++ library developer: 1. You implement a feature. 2. You work around bugs in older version of GCC and clang. 3. You work around bugs in the current version of MSVC. 4. You work around MSVC some more. 5. Eh, maybe this works? 6. No? 7. ??? 8. Profit.

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Jonathan Müller

@foonathan

1 year

This is a great post: Type systems for memory safety

Type Systems for Memory Safety

A survey of type systems for memory safety.

borretti.me

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Jonathan Müller

@foonathan

2 years

The feedback section of @jfbastien P2723 is perfect. #cpp

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Jonathan Müller

@foonathan

2 years

I've just tagged the first (beta) release of lexy, my C++ parser DSL library! It features parse tree generation, automatic error recovery, operator precedence parsing, Unicode support, and much more. #cpp #cplusplus

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Jonathan Müller

@foonathan

2 years

I've asked for ChatGPT's opinion on @jfbastien 's "zero-initialize objects of automatic storage duration" proposal. Are we sure it hasn't been trained on the committee mailing lists?!

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Jonathan Müller

@foonathan

2 years

The C++20 range based algorithms with projections are so much more convenient: std::find_if(vec.begin(), vec.end(), [&](T& elem) { return elem.member == needle; } vs std::ranges::find(vec, needle, &T::member);

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Jonathan Müller

@foonathan

3 months

Last committee meeting had an earthquake, this one has a fire alarm. Maybe it's a sign that we should stop working on C++.

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Jonathan Müller

@foonathan

6 years

I haven't forgotten that I have a blog: Tutorial: When to Write Which Special Member #cpp #cplusplus

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Jonathan Müller

@foonathan

3 years

I'm using this book underneath my computer monitor to make it higher. Highly recommended!

Introduction to Algorithms, Fourth Edition

@clrs4e

3 years

Dropping on 22 March 2022.

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Jonathan Müller

@foonathan

2 years

I'd like to use this opportunity to remind you about my website (for no particular reason): There you'll find a list of my talks and projects, as well as links to e.g. my GitHub account.

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Jonathan Müller

@foonathan

2 years

I'm currently writing a C interpreter, live on YouTube. Join the streams every Tuesday and Thursday at 17:00 CEST/CET. #livecoding #compiler #cpp

Jonathan Müller

C++, programming languages, and compilers.

www.youtube.com

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Jonathan Müller

@foonathan

1 year

Typo of the day: struct foo { foo& operator==(foo&& other); }; That was a fun segmentation fault.

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Jonathan Müller

@foonathan

7 years

I proudly present: cppast - A library to parse and work with the C++ AST #cpp #cplusplus

GitHub - standardese/cppast: Library to parse and work with the C++ AST

Library to parse and work with the C++ AST. Contribute to standardese/cppast development by creating an account on GitHub.

github.com

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Jonathan Müller

@foonathan

2 years

Today's debugging session was brought to you by foo(foo&& other) : ptr(std::exchange(ptr, nullptr)) {}

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Jonathan Müller

@foonathan

4 years

The things you learn about C from student submissions. This declares a global variable and four functions returning int.

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Jonathan Müller

@foonathan

5 years

Every global variable should be 0. non-existent, or 1. constexpr, which means it's immutable and initialized at compile time, or 2. constinit, which means it's mutable and initialized at compile time. That way, there is no static initialization order fiasco. #cpp #cplusplus

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Jonathan Müller

@foonathan

1 year

I've written a new blog post: Should we stop writing functions? (and use lambdas instead) #cpp #cplusplus

Should we stop writing functions? | think-cell

www.think-cell.com

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Jonathan Müller

@foonathan

2 years

C++ standard library in a nutshell: 1. Standardize a cool algorithm/container. 2. Early implementation is rushed and/or makes a decision that did not age well. 3. Early implementation cannot be changed due to ABI making it unusable. 4. Repeat with the new alternative.

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Jonathan Müller

@foonathan

7 months

Twitter in 2024.

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Jonathan Müller

@foonathan

2 years

Pro tip if you want to expose a lot of bugs: change your custom allocator implementation so that it immediately returns memory to the OS instead of caching it. Quick way to get use-after-free errors.

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Jonathan Müller

@foonathan

5 years

I recently needed to iterate over a null-terminated string via iterators, but I didn't want to calculate the end iterator up front. Luckily, this is easily done with a sentinel. Tutorial: C++20's Iterator Sentinels #cpp #cplusplus

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Jonathan Müller

@foonathan

2 years

I've been reading "C++ has become a legacy language" a lot recently; I'm curious what you think. Has or will C++ become a legacy language in the near future? Please RT for reach. #cpp #cplusplus #rust #safety

As a C++ user: YES legacy

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As a C++ user: NO legacy

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As a non-C++ user: YES

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As a non-C++ user: NO

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Jonathan Müller

@foonathan

2 years

TIL: division by -1 on x86 can also raise a division by zero error, which is a bit confusing to look at in the debugger. I also did not want to learn that.

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Jonathan Müller

@foonathan

5 months

@beyerstein It's illegal in Germany. If you can create a contract online by clicking a button, you must be able to cancel it online by clicking a button; cancellation must not be more difficult than subscribing.

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Jonathan Müller

@foonathan

6 years

Just wrote twenty slack messages explaining the difference between `T t;`, `T t{};`, `T()` and `T{}` (basically**** the first doesn't do zero-initialization, the others might) C++ truly is a language where initialization is a discussion among experts, for experts.

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Jonathan Müller

@foonathan

6 years

I published a new project I've been working on for the past two months or so: foonathan/array - an array based container library Featuring: std::vector equivalent with powerful customization for SBO & co, flat sets/maps etc #cpp #cplusplus

GitHub - foonathan/array: contiguous container library - arrays with customizable allocation, small...

contiguous container library - arrays with customizable allocation, small buffer optimization and more - foonathan/array

github.com

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Jonathan Müller

@foonathan

2 years

My malloc blog post results in two reactions: If you're coming from a C++ perspective, you see malloc as a low-level API that you only use for absolute performance. Then you agree. If you're coming from C, malloc is your convenient allocator and any change a complication.

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Jonathan Müller

@foonathan

5 years

New blog post about naming with a small detour about the C++ object model, because why not. Naming Things: Implementer vs. User Names Thanks to @gregcons @CppCon talk about naming for giving me the proper term for the symptom! #cplusplus #cpp

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Jonathan Müller

@foonathan

2 years

I've surpassed 10k followers! When I created this twitter account almost exactly 8 years ago, I had no idea how much it would change my life: it caused me to do open source projects, start a blog, give talks, and I got to meet so so many amazing people. Thank you all.

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Jonathan Müller

@foonathan

2 years

@vzverovich Why preparse all possible inputs? It's enough to preparse the inputs of the benchmark.

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Jonathan Müller

@foonathan

4 years

A while back, I've started to write comments as full sentences, with punctuations and everything. I've noticed that I am consistently using "we" in the comments. // Check, whether we've reached the end. // We need to handle -1 as well. etc. I sort of like it.

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Jonathan Müller

@foonathan

4 years

The nice thing about writing a library that is almost completely templates: you have really high code coverage by default. Functions are only measured if you have a test that instantiates them. If you want 100% code coverage, just delete all tests!

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Jonathan Müller

@foonathan

2 years

Since lots of new languages are popping up, I've blogged about something they should try: New integer types I’d like to see

New integer types I'd like to see

(Most) C++ implementations provide at least 8, 16, 32, and 64-bit signed and unsigned integer types. There are annoying implicit conversions, discussions about undefined behavior on overflow (some...

www.foonathan.net

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Jonathan Müller

@foonathan

6 years

I've created a couple of docker images for building C++ projects. They're very lightweight and are designed to create fully statically linked executables compatible with any Linux distribution. #cpp #cplusplus #docker

GitHub - foonathan/docker: Containers for building C++ on CI

Containers for building C++ on CI. Contribute to foonathan/docker development by creating an account on GitHub.

github.com

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Jonathan Müller

@foonathan

3 years

I wrote a short blog post that might be interesting for the C++ bloggers out there: Tutorial: Interactive code snippets with Hugo and @CompileExplore #cpp #cplusplus

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Jonathan Müller

@foonathan

7 years

How to detect that your introductory C++ lecture is bad, part 42: using namespace std; list<Employee*> employees; void main() { ... }

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Jonathan Müller

@foonathan

6 years

Thank you, @google , that's exactly what I meant.

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Jonathan Müller

@foonathan

1 year

@vzverovich Google plans to be Carbon neutral by 2030.

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Jonathan Müller

@foonathan

2 years

For me personally, Rust has two advantages over C++: 1. A modern, clean, usable standard library. 2. Only having to support a single compiler frontend. Now that GCC will gain a Rust frontend, the second advantage is gone.

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Jonathan Müller

@foonathan

2 years

@jfbastien I've proposed [[uninitialized]] back in 2017:

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Jonathan Müller

@foonathan

6 years

Pro tip for custom compile-time error messages: template <typename ... Args> constexpr bool error_with = false; Then: static_assert(error_with<A, B, C>, "A not compatible with B and C"); clang will show: static_assert failed ... 'error_with<int, char, float>' "A not ..."

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Jonathan Müller

@foonathan

2 years

The nice thing about C++ is that you can be the first person to use a certain combination of features! Today, unnamed bit fields and has_unique_object_representations. Bonus points for broken operator== on clang. #cpp #cplusplus

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Jonathan Müller

@foonathan

3 years

Pro tip: Don't install a compiler update while currently compiling with that compiler. You'll get really weird error messages.

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Jonathan Müller

@foonathan

3 years

@lefticus It depends. Here it is singular, as `Color c` will only ever hold one color. But if your enum is used as flag, one enum variable might hold a combination of flags, so it is plural.

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Jonathan Müller

@foonathan

4 years

I'm releasing a new library tomorrow! I've been working on it for the past year or so, going through various designs, trying things out, and now I've finally got something ready to be released. If anyone wants to proofread the tutorial I've just written, let me know.

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Jonathan Müller

@foonathan

6 years

std::is_array<std::array<T, 5>> is std::false_type. Because std::array is not an array, obviously. (Yes, I know why it is false)

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Jonathan Müller

@foonathan

2 years

There is a big discussion about Linux and Rust's safety, but most seems to focus on an earlier email by Linus. I find this reply more interesting: I think those functions should be unsafe as they can lead to UB, but Linus doesn't seem to care much #rust

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Jonathan Müller

@foonathan

2 years

C++ is a low-level language: instead of the language features you actually want, you have tools to build them. Want customization functions? Build something using friend functions, arcane look up rules and overloading. Want to tweak move behavior? Use this weird reference type.

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Jonathan Müller

@foonathan

6 years

Naming is hard, part N of ∞: I didn't implement a feature I had in mind because I didn't know how to name it.

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Jonathan Müller

@foonathan

2 years

Tools ranked by how long it takes to fix their error messages, ascending: 0. clang-tidy 1. C compiler 2. C++ compiler (non-template) 3. CMake 4. C++ compiler (template) ... 999. Linker

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Jonathan Müller

@foonathan

3 years

WTF was I supposed to do?! Wordle 243 X/6 🟩🟩🟨🟨⬜ 🟩🟩🟩⬜🟩 🟩🟩🟩⬜🟩 🟩🟩🟩⬜🟩 🟩🟩🟩⬜🟩 🟩🟩🟩⬜🟩

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Jonathan Müller

@foonathan

3 years

I wrote my thoughts about writing a new type vs adding new functions to change behavior: saturating_add vs. saturating_int – new function vs. new type? #cpp #cplusplus

`saturating_add` vs. `saturating_int` -- new function vs. new type?

Suppose you want to do integer arithmetic that saturates instead of overflowing. The built-in operator+ doesn’t behave that way, so you need to roll something yourself. Do you write a saturating_ad...

www.foonathan.net

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Jonathan Müller

@foonathan

3 years

The problems of an open source maintainer: 1. Write code. 2. Test code. 3. Document code. 4. Workaround MSVC. 5. Crash GCC in the process. 6. Spend an afternoon running creduce. 7. ??? (I'm not here yet) 8. Release. Only 1. and 8. is actually fun...

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Jonathan Müller

@foonathan

2 years

Carbon has a feature that I've been thinking about for years, and which has a lot of potential, so I've blogged about it: Carbon’s most exciting feature is its calling convention #carbon #CarbonLang

Carbon's most exciting feature is its calling convention

Last week, Chandler Carruth announced Carbon, a potential C++ replacement they’ve been working on for the past two years. It has the usual cool features you expect from a modern language: useful...

www.foonathan.net

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Jonathan Müller

@foonathan

4 months

@djwesallen @matttomic No, there are obviously 9 teams in the top half, 9 in the bottom half, and 2 in the middle half.

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Jonathan Müller

@foonathan

11 months

I've written a new blog post: C++ needs undefined behavior, but maybe less #cpp #cplusplus

C++ needs undefined behavior, but maybe less | think-cell

www.think-cell.com

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Jonathan Müller

@foonathan

2 years

Functions should be small. What if you have a big function that does three things in sequence though? If you extract it into three functions step1(); step2(); step3(), this looses information about the potential order. Ping @tvaneerd

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Jonathan Müller

@foonathan

6 years

@zygoloid @CppCon template <auto V>constexpr bool i(){return *(__PRETTY_FUNCTION__ + 14) >> 6;} template <class E, size_t ... D>constexpr auto e(index_sequence<D...>){auto r=0;((i<E(D)>() && ++r), ...);return r;} template <typename E> constexpr auto enum_size = e<E>(make_index_sequence<32>{});

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Jonathan Müller

@foonathan

1 year

In some compiler messages, you are reminded that C++ doesn't support default-int. While I'm sure this was helpful to include 40 years ago, I'd argue that most people are getting confused by it since they have no idea what default int is. #cpp

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Jonathan Müller

@foonathan

2 years

Days since the last compilation error because I forgot a constexpr on a function: 0 Remember, if you don't have a test that calls your constexpr function at compile-time, your function isn't really constexpr!

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Jonathan Müller

@foonathan

3 years

Writing documentation is great way to discover bugs and interface inconsistencies. It is also great to go "ah, I should probably do that here" only to discover that you already thought of that, and it's been implemented for ages...

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Jonathan Müller

@foonathan

7 years

Hey, I have decided to setup a Patreon. If you like my work, I'd love to get your support. Thank you all for blog post comments, Github stars, issues and PRs and way too many followers!

creating C++ libraries, blog posts and talks

www.patreon.com

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Jonathan Müller

@foonathan

6 years

Immediately-Invoked Function Expression: struct iife {}; template <typename Func> auto operator+(iife, const Func& f) { return f(); } #define IIFE(T) iife{} + [&]() -> T // x can be const, even though... const auto x = IIFE(int) { ... // complex init here }; cc @gregcons

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Jonathan Müller

@foonathan

3 years

New blog post: I accidentally wrote a Turing-complete parsing library #cpp #cplusplus

I accidentally wrote a Turing-complete parsing library

I’m currently working on lexy, a C++ parsing DSL library: you describe how input should be parsed, and lexy generates code for it, taking care of error recovery, parse tree generation, and parse...

www.foonathan.net

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Jonathan Müller

@foonathan

6 years

In the C++ UG meeting in Aachen last month a string switch based on tries was presented. This inspired me to write a tokenizer based on the same mechanism. The result is a very fast C++14 (compile-time) tokenizer: #cpp #cplusplus

GitHub - foonathan/lex: Replaced by foonathan/lexy

Replaced by foonathan/lexy. Contribute to foonathan/lex development by creating an account on GitHub.

github.com

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Jonathan Müller

@foonathan

6 years

Exams are over, time for a new blog post: This is the C++ heaviest post of the series where I talk about <=> Mathematics behind Comparison #4 : Three-Way Comparison #cpp #cplusplus

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Jonathan Müller

@foonathan

4 years

Schrödinger's directory.

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Jonathan Müller

@foonathan

6 years

I've started a series on my blog: Mathematics behind Comparison #1 : Equality and Equivalence Relations #cpp #cplusplus

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Jonathan Müller

@foonathan

6 years

I may have created yet another library... foonathan/tiny: low-level library featuring tombstones, improved bitfields (tiny types) and other tricks to make your types as small as possible. #cpp #cplusplus

GitHub - foonathan/tiny: low-level library for minimizing the size of your types

low-level library for minimizing the size of your types - foonathan/tiny

github.com

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Jonathan Müller

@foonathan

7 years

The 3 most complex parts of C++: 1. std::memory_order_consume 2. std::launder 3. variable initialization rules

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Jonathan Müller

@foonathan

2 years

I'd normally wouldn't quote tweet to disagree but since this tweet blew up, I feel I need to for visibility. What he's saying here is false and misleading. Circle isn't being censored from the subreddit, the occupation of the mod is irrelevant, and only a single post was removed

Sean Baxter

@seanbax

2 years

Circle is being censored from the C++ reddit. I built a C++ compiler from scratch. I'm documenting my work on extensions that are aimed at keeping it from going extinct. But a mod who works for a commercial vendor is now pulling down posts. This is terrible for free discourse.

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Jonathan Müller

@foonathan

2 years

I'm speaking later today about coroutines in C++ vs Rust at @cpponsea . No Rust knowledge necessary.

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Jonathan Müller

@foonathan

6 years

Every C++ class should be exactly one of: * abstract (base class in hierarchy) * polymorphic *and* final (derived class in hierarchy) * non-polymorphic, public dtor (regular class) * non-polymorphic, protected dtor (non-polymorphic base classes) #cpp #cplusplus

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