{"id":17278629,"url":"https://github.com/kris-jusiak/vc","last_synced_at":"2025-04-14T09:22:41.815Z","repository":{"id":146695367,"uuid":"84686284","full_name":"kris-jusiak/vc","owner":"kris-jusiak","description":"Virtual Concepts","archived":false,"fork":false,"pushed_at":"2017-03-28T22:24:42.000Z","size":74,"stargazers_count":8,"open_issues_count":1,"forks_count":1,"subscribers_count":3,"default_branch":"master","last_synced_at":"2025-03-27T22:43:09.221Z","etag":null,"topics":["concepts","dependency-injection","dynamic-polymorphism","mocking","static-polymorphism","type-erasure"],"latest_commit_sha":null,"homepage":"","language":"C++","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":null,"status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/kris-jusiak.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":null,"code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null,"governance":null,"roadmap":null,"authors":null,"dei":null,"publiccode":null,"codemeta":null}},"created_at":"2017-03-11T23:19:05.000Z","updated_at":"2024-01-05T15:24:34.000Z","dependencies_parsed_at":"2023-04-20T20:07:05.945Z","dependency_job_id":null,"html_url":"https://github.com/kris-jusiak/vc","commit_stats":null,"previous_names":["kris-jusiak/vc","krzysztof-jusiak/vc"],"tags_count":0,"template":false,"template_full_name":null,"repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/kris-jusiak%2Fvc","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/kris-jusiak%2Fvc/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/kris-jusiak%2Fvc/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/kris-jusiak%2Fvc/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/kris-jusiak","download_url":"https://codeload.github.com/kris-jusiak/vc/tar.gz/refs/heads/master","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":248852251,"owners_count":21171854,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["concepts","dependency-injection","dynamic-polymorphism","mocking","static-polymorphism","type-erasure"],"created_at":"2024-10-15T09:12:33.853Z","updated_at":"2025-04-14T09:22:41.793Z","avatar_url":"https://github.com/kris-jusiak.png","language":"C++","funding_links":[],"categories":[],"sub_categories":[],"readme":"\u003ca href=\"http://www.boost.org/LICENSE_1_0.txt\" target=\"_blank\"\u003e![Boost Licence](http://img.shields.io/badge/license-boost-blue.svg)\u003c/a\u003e\n\n---------------------------------------\n\n# Virtual Concepts\n\n### Concept\n```cpp\ntemplate\u003cclass T\u003e\nconst auto Equality_comparable =\n  $requires(T)(auto a, auto b) (\n    bool(a == b),\n    bool(a != b)\n  );\n```\n\n```cpp\ntemplate\u003cclass T\u003e\nconst auto Iterator() {\n  return CopyConstructible\u003cT\u003e \u0026\u0026\n         CopyAssignable\u003cT\u003e \u0026\u0026\n         Destructible\u003cT\u003e \u0026\u0026\n         $requires(T)(auto\u0026\u0026 t) (\n           *t,\n           typename decltype(t)::type\n         );\n  }\n}\n```\n\n```cpp\ntemplate\u003cclass T, class F, class R, class... Ts\u003e\nconst auto Callable(F f) {\n  return $requires(T)(auto\u0026\u0026 t, Ts... args) (\n    R((t.*f)(args...));\n  )\n}\n```\n\n```cpp\ntemplate\u003cclass T, class R, class... Ts\u003e\nconst auto Creatable = Callable\u003cT, R(Ts...)\u003e($(create));\n```\n\n```cpp\nstruct Readable {\n  template\u003cclass T\u003e\n  auto operator()() {\n    return CopyConstructible() \u0026\u0026\n       $requires(T)(auto\u0026\u0026 t, std::ostream\u0026 os) (\n          os = (os \u003c\u003c t)\n       ) \u0026\u0026\n       Callable\u003cT, void(int)\u003e($(read));\n  }\n};\n```\n\n### Implementation\n```cpp\nstruct FileReader {\n  void read(int) const {\n    std::cout \u003c\u003c __PRETTY_FUNCTION__ \u003c\u003c std::endl;\n  }\n};\n\nstd::ostream\u0026 operator\u003c\u003c(std::ostream\u0026 os, FileReader\u0026) {\n  return os;\n}\n```\n\n### Usage\n```cpp\nint main() {\n  // constraint checking\n  static_assert(Equality_comparable\u003cint\u003e, \"\");\n  static_assert(Readable{}.operator()\u003cFileReader\u003e(), \"\");\n  \n  // template mocking\n  testing::GMock\u003cReadable\u003e mockReadable;\n  EXPECT_CALL(mockReadable, read, 42);\n  mockReadable.read(42);\n  \n  // type erasure - dynamic dispatch\n  type_erasure::any\u003cReadable\u003e readable = FileReader{};\n  readable.read(42);\n  \n  // type erasure mocking\n  readable = GMock\u003cReadable\u003e{};\n  EXPECT_CALL(mock, read, 42);\n  readable.read(42);\n}\n```\n\n### Dependency Injection - [[Boost].DI](https://github.com/boost-experimental/di)\n```cpp\ntemplate\u003cclass TReader = Readable\u003e // = 'Concept'\nclass App {\n  TReader reader;                       // static dispatch\n  type_erasure::any\u003cPrintable\u003e printer; // dynamic dispatch\n  \npublic:\n  App(TReader reader, type_erasure::any\u003cPrintable\u003e printer)\n   : reader(reader), printer(printer)\n  { }\n  \n  void run() {\n    printer.print(reader.read());\n  }\n};\n\nint main() {\n  const auto injector = di::make_injector(\n     di::bind\u003cReadable\u003e.to\u003cFileReader\u003e()\n     di::bind\u003cPrintable\u003e.to\u003cConsolePrinter\u003e()\n  );\n  \n  injector.create\u003cApp\u003e().run();\n}\n```\n\n### Testing\n```cpp\n\"should print read text\"_test = [] {\n  constexpr auto value = 42;\n\n  auto [sut, mocks] = testing::make\u003cApp\u003e(); // creates System Under Test\n                                            // and Mocks\n\n  InSequence sequence;\n  EXPECT_CALL(mocks\u003cReadable\u003e(), read).WillOnce(Return(value));\n  EXPECT_CALL(mocks\u003cPrintable\u003e(), print, value);\n\n  sut.run();\n};\n```\n\n---\n\n## Dependencies\n* Concepts\n  * [STL](http://en.cppreference.com/w)\n* Type Erasure (any)\n  * [dyno](https://github.com/ldionne/dyno)\n    * [Boost.Hana](https://github.com/boostorg/hana)\n    * [CallableTraits](https://github.com/badair/callable_traits)\n* Mocking (GMock)\n  * [GUnit](https://github.com/cpp-testing/GUnit)\n    * [Google Test/Mock](https://github.com/google/googletest)\n* Dependency Injection\n    * [[Boost].DI](https://github.com/boost-experimental/di)\n\n## References\n* [Concept Checking in C++11](http://ericniebler.com/2013/11/23/concept-checking-in-c11) | [Type requirements in C++](http://pfultz2.com/blog/2014/08/17/type-requirements)\n* [A bit of background for concepts](https://isocpp.org/blog/2016/02/a-bit-of-background-for-concepts-and-cpp17-bjarne-stroustrup)\n* [Concepts Lite](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3580.pdf)\n* [Vitual Concepts Proposal](https://github.com/andyprowl/virtual-concepts/blob/master/draft/Dynamic%20Generic%20Programming%20with%20Virtual%20Concepts.pdf)\n* [Concepts driven design with DI](http://boost-experimental.github.io/di/concepts-driven-design-with-di)\n* [Static reflection](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0194r0.pdf)\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fkris-jusiak%2Fvc","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fkris-jusiak%2Fvc","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fkris-jusiak%2Fvc/lists"}