FredEmmott::bindline
FredEmmott::bindline is a header-only library to compose functions in a readable way, similar to std::ranges::views. It is most useful in asynchronous code, such as event handlers, other callbacks, and coroutines.
This library was originally an internal implementation detail of OpenKneeboard, which uses it heavily.
Examples
auto f = &MyClass::some_func
// Store an `std::weak_ptr` or `winrt::weak_ref`, but when invoking:
// 1. convert back to a strong ref
// 2. return without invoking if the ref is stale (i.e. `nullptr`)
| bind_refs_front(this)
// Automatically switch thread when invoked
| bind_winrt_context(winrt_apartment_context_or_dispatcher_queue())
// if some_func() takes N parameters, require invocing with N + 2
// parameters; this can be useful for event handlers
| drop_n_back<2>();
f(args...);
Common errors can be automatically detected at compile-time:
// This is fine:
f | bind_refs_front(this) | bind_winrt_context(ctx);
/* This is an error:
*
* functions on the right wrap functions on the left, and you probably want to
* promote the weak ref to a strong ref _after_ switching threads:
*/
f | bind_winrt_context(ctx) | bind_refs_front(this);
To bypass validation, use bind_suppress_validation().
Terminology
- a functor is an object that can be invoked, i.e. implements
operator() - a pipeline of composed functions is a bindline