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https://github.com/voltra/cpp-as-is
A C++17 Library for generic type queries or conversions, based on Herb Sutter's talk at CPPCon 2021 (https://www.youtube.com/watch?v=raB_289NxBk)
https://github.com/voltra/cpp-as-is
cplusplus cplusplus-17 hacktoberfest
Last synced: about 8 hours ago
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A C++17 Library for generic type queries or conversions, based on Herb Sutter's talk at CPPCon 2021 (https://www.youtube.com/watch?v=raB_289NxBk)
- Host: GitHub
- URL: https://github.com/voltra/cpp-as-is
- Owner: Voltra
- Created: 2023-09-05T13:25:47.000Z (about 1 year ago)
- Default Branch: main
- Last Pushed: 2023-10-22T10:01:25.000Z (about 1 year ago)
- Last Synced: 2023-10-22T11:20:52.326Z (about 1 year ago)
- Topics: cplusplus, cplusplus-17, hacktoberfest
- Language: CMake
- Homepage:
- Size: 132 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# cpp-as-is
[](https://github.com/Voltra/cpp-as-is/actions/workflows/ci.yml)
[](https://codecov.io/gh/Voltra/cpp-as-is)
[](https://github.com/Voltra/cpp-as-is/actions/workflows/codeql-analysis.yml)
## About cpp-as-is
A C++17 Library for generic type queries or conversions, based on [Herb Sutter's talk at CPPCon 2021](https://www.youtube.com/watch?v=raB_289NxBk)
## Usage
```cpp
#include
int main() {
using namespace cpp_as_is;
auto someWrappedValue = getValue();
if (is(someWrappedValue)) {
int value = as(someWrappedValue);
std::cout << "value: " << value << '\n';
} else {
std::cout << "No value";
}
return 0;
}
```
## Available conversions & queries
NB: All specializations and overloads are conditionally present using `__has_include` directives
Legend: **to** means both `is` and `as` are available, **is** means only `is` is available
* `T` to `T`
* `T*` to `T`
* `T*` is `std::nullptr_t`
* `T*` to `U*`
* [`std::any`](https://en.cppreference.com/w/cpp/utility/any) to `T`
* [`boost::any`](https://www.boost.org/doc/libs/1_61_0/doc/html/boost/any.html) to `T`
* [`std::expected`](https://en.cppreference.com/w/cpp/utility/expected) to `T`
* `std::expected` to [`std::unexpected`](https://en.cppreference.com/w/cpp/utility/expected/unexpected)
* [`BOOST_OUTCOME_V2_NAMESPACE::outcome`](https://www.boost.org/doc/libs/1_83_0/libs/outcome/doc/html/tutorial/essential/outcome.html) to `T`
* `BOOST_OUTCOME_V2_NAMESPACE::outcome` to `ErrCode`
* `BOOST_OUTCOME_V2_NAMESPACE::outcome` to `ExcPtr`
* [`BOOST_OUTCOME_V2_NAMESPACE::result`](https://www.boost.org/doc/libs/1_83_0/libs/outcome/doc/html/tutorial/essential/result.html) to `T`
* `BOOST_OUTCOME_V2_NAMESPACE::result` to `ErrCode`
* [`std::future`](https://en.cppreference.com/w/cpp/thread/future) to `T`
* [`std::shared_future`](https://en.cppreference.com/w/cpp/thread/shared_future) to `T`
* [`std::experimental::future`](https://en.cppreference.com/w/cpp/experimental/future) to `T`
* [`std::experimental::shared_future`](https://en.cppreference.com/w/cpp/experimental/shared_future) to `T`
* [`boost::fibers::future`](https://www.boost.org/doc/libs/1_83_0/libs/fiber/doc/html/fiber/synchronization/futures/future.html) to `T`
* [`std::optional`](https://en.cppreference.com/w/cpp/utility/optional) to `T`
* `std::optional` is [`std::nullopt_t`](https://en.cppreference.com/w/cpp/utility/optional/nullopt)
* [`boost::optional`](https://www.boost.org/doc/libs/1_83_0/libs/optional/doc/html/index.html#optional.introduction) to `T`
* [`std::shared_ptr`](https://en.cppreference.com/w/cpp/memory/shared_ptr) to `T`
* [`std::unique_ptr`](https://en.cppreference.com/w/cpp/memory/unique_ptr) to `T`
* [`std::variant`](https://en.cppreference.com/w/cpp/utility/variant) to `T`
## Extendability
There are two extension points:
* `cpp_as_is::ext::is_conversion_traits` for `cpp_as_is::is(from)`, as described by the `cpp_as_is::InspectableWithIs` concept
* `arg_type` represents the expected argument type when calling `is`
* `static inline bool matches(const arg_type &) noexcept` is the static member function that checks whether the types "match" (it should be constexpr if possible, though it's not required)
* `cpp_as_is::ext::as_conversion_traits` for `cpp_as_is::as(from)`, as described by the `cpp_as_is::IsConvertibleWithAs` concept
* `arg_type` represents the expected argument type when calling `as`
* `return_type` represents the expected return type of `as`
* `static inline return_type convert(arg_type) noexcept` is the static member function that handles converting from `From` to `To`
As a rule:
* if you're going to extend `as`, you must first extend `is`
* provide as many overloads for `as_conversion_traits::convert` as possible (e.g. const ref, rvalue, etc...)
## More Details
* [Dependency Setup](README_dependencies.md)
* [Building Details](README_building.md)
* [Troubleshooting](README_troubleshooting.md)
* [Docker](README_docker.md)