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Continuable 2.0.0
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@Naios Naios released this 30 Jan 21:39
· 378 commits to master since this release
2.0.0
4aaafb5

Zero cost futures now with error handling and co_await support

In version 2.0 the library was heavily improved in multiple ways:

Error handling

Usually it is inconvenient to handle error codes and exceptions in an asynchronous context, as we all know std::future supports error handling through exceptions already. We now introduce this capability to the continuable library while allowing error codes to be used as well.

Consider the function cti::continuable<> get_bad_continuable() which always resolves through an error, then you may handle the error code or exception as following:

get_bad_continuable()
  .then([] {
    // ... never invoked
  })
  .then([] {
    // ... never invoked as well
  })
  .fail([] (std::exception_ptr e) {
    try {
      std::rethrow_exception(e);
    } catch(std::exception const& e) {
      // Handle the exception here
    }
  });

Abstracting callbacks as promises

Since a callback may be called through an error or result the cri::promise class was added in order ro provide a similar interface to std::promise:

auto http_request(std::string url) {
return cti::make_continuable<std::string>([url = std::move(url)](cti::promise<std::string> /*or auto&&*/ promise) {
  // Perform the actual request through a different library,
  // resolve the promise upon completion of the task.
  promise.set_value("<html> ... </html>");
 // ...or promise.set_exception(...);
});
}

co_await support

Experimental coroutine (co_await and co_return) support was added, this is available on MSVC 2017 and Clang 5.0.

int i = co_await cti::make_continuable<int>([](auto&& promise) {
  promise.set_value(0);
});

Minor improvements

The library was improved in other ways:

  • constexpr and noexcept improvements
  • Compile-time improvements
  • Documentation improvements

Header split

Since the overall library size was increased the headers were split into smaller chunks.

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