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Introduction

Mitama.Result is a header only C++20 library for error handling.

Installation

Dependencies

  • fmt: 9.0.0 or higher

Supported OS / Compiler / Language Standard

  • OS

    • Linux
    • Apple Darwin
    • (Windows)

  • Compilers

    • gcc >= 11
    • clang >= 15
    • Latest preview version of MSVC only

  • Language Standards

    • C++20
    • (MSVC: only support /std:c++latest)

CMake

  • First, clone mitama-cpp-result repository.
$ git clone https://github.com/LoliGothick/mitama-cpp-result.git
  • Second, run CMake and Make commands:
$ cd mitama-cpp-result
$ cmake ..
$ make install

Manually

  • First, clone mitama-cpp-result repository.
$ git clone https://github.com/LoliGothick/mitama-cpp-result.git
  • Second, add path/to/mitama-cpp/include to include path.

Basic Usage

Here is a bad code.

bool func(int a) {
  if ( first check )
    return false;
  if ( second check )
    return false;
  if ( third check )
    return false;
  // function body...
  return true;
}
// ...
assert(func(42));

If this program fail to assert, you don't know the reason for the error.

Rewrite this code using result.

auto func(int a) -> mitama::result<int, std::string> {
  if ( first check )
    return mitama::failure("first check failed"); // early return
  if ( second check )
    return mitama::failure("second check failed"); // early return
  if ( third check )
    return mitama::failure("third check failed"); // early return
  // function body...
  return mitama::success(42);
}
// ...
int value = func(42).unwrap();

Even if this program fail to assert, you can get the reason for the error.