maddy VS doctest

Since I offloaded my markdown parsing to maddy, I did not test for it because it was not my own code. As a result, it was difficult to find parts that I could test. I mostly created my test cases for end to end testing. Since the number of things to test for is always numerous, I ended up finding a few things I could test for. But, I definitely am not satisfied with the number of tests I currently have and will be adding more in the future.

Across all the JavaScript-based SSGs, palpatine is developed from the ground up using C++ and CMake as the build system. As the developer and maintainer of palpatine my main concern is to make it lightning fast compared to others. Currently, palpatine1.5 can generate a static site in less than 1 second. I've also made sure that it is easy to use, with a simple command line interface. The documentation is also precise and easy to follow. However, it is lacking one of the core features, supporting markdown files fully. I've been working on this feature for the past few days and I found a header-only Markdown parser library maddy. But it seems that it has been more than a year since the last commit was made to the library. I'm not sure if it is still being maintained. CMake was quite upset about how outdated it was.

Taking inspiration from Docusaurus, I added full markdown parsing support to my SSG. I chose to add this because it was a core component of my SSG that remained incomplete. Instead of adding a nice-to-have feature, I figured it would be best to complete the core functionality of my SSG first. Instead of coding my own markdown parsing, it was much easier to simply use a markdown parsing library which already existed. I did this by using a maddy, a C++ markdown parsing library. The process of using the library was very straightforward, although calling its methods did noticeably slow down the html generation. After verifying that it worked with my SSG, I removed my initial implementation of markdown parsing.

I have never used "tools" for unit-tests, only web sites that show the results of the tests or code coverage. For C++ I prefer https://github.com/doctest/doctest but most companies I worked for use Catch2.

Do the README and tutorial not explain it well enough? It's a framework for automated unit testing.

This is, honestly, super easy to get going. Nowadays you have a ton of libraries and more-than-decent build systems. With Meson/CMake and Conan/Vcpkg I can set up a project with testing in 3 minutes. Also, I think that at the end of the day you want your tests to live somewhere else. But if you want to embed them, you also have https://github.com/doctest/doctest.

Write some tests. They can find bugs early and give you confidence that your code works so far. That doesn't have to be anything fancy, e.g. with doctest:

Keep in mind https://github.com/doctest/doctest/issues/554. Also, doctest lacks: - Matchers - Data generators - Benchmarking - ...

Your requirements can easily simulated on paper (like increase the speed once, twice, ...), then translated to unit-tests with a framework like https://github.com/doctest/doctest.

I like working in C++, after a decade of working in Java, Python, Javascript and Clojure, I find working in C++ (which I learned before these other languages) to be quite fun and pleasant, at least with relatively modern C++.

I've been, on and off, working on a little toy game engine, for a few years. Its a mix of keeping up with C++ advancements, learning various concepts like physically based rendering, and just the fun of crafting a big project, with no constraints other than my time and ability, no deadlines, no expectation of releasing anything. Its cathartic and enjoyable. I really do enjoy it.

Last September, I got frustrated with something I was working on in a more serious capacity. It was some server software, it responded to HTTP requests, it accessed third party services over HTTP and Websockets, it talked to a Postgres database. Overall it was an event driven system that transformed data and generated actions that would be applied by talking to third party services. The "real" version was written in Clojure and it worked pretty well. I really like Clojure, so all good.

But because I was frustrated with some things about how it ran and the resources it took up, I wondered what it would be like if I developed a little lean-and-mean version in C++. So I gave it a try as a side project for a few weeks. I used doctest[1] for testing, immer[2] for Clojure-like immutable data structures, [3] lager for Elm-like application state and logic management, Crow[4] for my HTTP server, ASIO[5] and websocketpp[6] for Websockets, cpp-httplib[7] as a HTTP client and PGFE[8] for Postgres, amongst some other little utility libraries. I also wrote it in a Literate Programming style using Entangled[9], which helped me keep everything well documented and explained.

For the most part, it worked pretty well. Using immer and lager helped keep the logic safe and to the point. The application started and ran very quickly and used very little cpu or memory. However, as the complexity grew, especially when using template heavy libraries like lager, or dealing with complex things like ASIO, it became very frustrating to deal with errors. Template errors even on clang became incomprehensible and segmentation faults when something wasn't quite right became pretty hard to diagnose. I had neither of these problems working on my game engine, but both became issues on this experiment. After a few weeks, I gave up on it. I do think I could have made it work and definitely could go back and simplify some of the decisions I made to make it more manageable, but ultimately, it was more work than I had free time to dedicate to it.

So my experience was that, yes, you can write high level application logic for HTTP web backends in C++. You can even use tools like immer or lager to make it feel very functional-programming in style and make the application logic really clean. Its not hard to make it run efficiently both in terms of running time and memory usage, certainly when comparing to Clojure or Python. However, I found that over all, it just wasn't as easy or productive as either of those languages and I spent more time fighting the language deficiencies, even with modern C++, than I do when using Clojure or Python.

I think I would think very long and hard before seriously considering writing a web backend in C++. If I had the time, I'd love to retry the experiment but using Rust, to see how it compares.

[1] https://github.com/doctest/doctest

[2] https://github.com/arximboldi/immer

[3] https://github.com/arximboldi/lager

[4] https://github.com/CrowCpp/crow

[5] https://think-async.com/Asio/

[6] https://www.zaphoyd.com/projects/websocketpp/

[7] https://github.com/yhirose/cpp-httplib

[8] https://github.com/dmitigr/pgfe

[9] https://entangled.github.io/

For stuff like this which is very easy to test (very predefined input vs output), I highly suggest using some testing framework. Catch2 is great, but there is also doctest and good ole googletest. If you do this, it would also be a great intro to CI, where you do some plumbing on github or gitlab where every commit causes a build to happen on their servers and run through the unit tests, and if it passes it gets merged into master.

doctest is my favorite framework. Really simple to use, header only, supports compile-time tests, lots of features and it works well with cmake.