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posixpp: Repository summary

The main posixpp library and associated tests.

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Rev. Time Author Message
5f78080a2b88 2022-12-08 23:28:42 Eric Hopper tip Add some comments inspired by a ChatGPT session.
901261d5fd16 2022-01-12 01:03:33 Eric Hopper Add sample compile command so I don't have to reconstruct...
b1b7172b6000 2022-01-11 04:41:07 Eric Hopper Merge with other clang-tidy cleanups.
adc44f7e5a6f 2022-01-11 04:22:51 Eric Hopper Add support for fcntl + wrapper for F_DUPFD and F_DUPFD_C...
857a394ad592 2022-01-11 04:19:25 Eric Hopper Fix various random clang-tidy complaints.
15ec4b4900e4 2022-01-11 03:43:12 Eric Hopper Remove excess blank line.
65d4804a6639 2022-01-11 03:41:44 Eric Hopper Silence "return from norreturn" warnings.
0985bb9e2c34 2022-01-11 03:40:46 Eric Hopper Fix destructor for union to be constexpr so expected<T> d...
a69f8a0de90c 2021-06-30 02:38:38 Eric Hopper Fix various clang-tidy complaints.
9eb80934ba7d 2021-05-11 01:07:00 Eric Hopper Fix 'move to self' bug.

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Name Rev. Time Author
tip 5f78080a2b88 2022-12-08 23:28:42 Eric Hopper


Name Rev. Time Author Message
default 5f78080a2b88 2022-12-08 23:28:42 Eric Hopper Add some comments inspired ...


A pure C++ Posix interface

With this project, I intend to implement many parts of Posix in pure C++ without any reliance on libc. There are several motivations for this:

  1. glibc and pthreads are very bloated with features that are rarely used in most programs.
  2. System calls are not exposed to the C++ optimizer in a useful way. The register stores and loads required to make them work can often be combined with the calculations a program is already doing so that the values mysteriously appear in the registers when needed instead of having to be moved there just before the system call.
  3. errno is a horrible hack that is a throwback to a single threaded era and a language that could not sensibly return both error conditions and proper return values from the same function. errno is the bane of clean error handling, and it requires expensive to access thread local storage to implement. Error returns should not be global variables.

For motivation 2 I intend to implement the system call interface for many architectures (and potentially many operating systems) as inline assembly inside of inline functions.

For motivation 3, a simple expected type is used for error handling at every level of the interface. This also causes default error handling (if you just assume the expected object always contains the expected value) to throw an exception whenever errors are ignored. And if you purposely check for errors, all code relating to exceptions will be optimized out of existence.

Ideally, parts of the C++ standard library that rely on operating system facilities would also be implemented in this library.

For example, pthreads is a terrible interface, designed when threading was mysterious, strange, complex, and rare. And it was designed for old ideas about how threads should synchronize. It's far more expensive to use than it should be for simple mutexes and condition variables.

IOstreams isn't the best part of C++. But, being able to implement it while ignoring C's stdio might make things easier.

Lastly, it would be really nice to have a preprocessor namespace that isn't chock full macro definitions (most of which are just using the preprocessor to implement constants in a throwback to the days before C90). And it would be nice to have names and types for various flags passed to various system calls that made it easier to write correct programs.

As a side note, I really like Mercurial, and so the canonical repo is at OSDN: https://osdn.net/projects/posixpp/scm/hg/posixpp

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