stripekit::OnceCallback< Args > Class Template Reference

Makes a callback safe to hand to code that might fire it more than once. More...

#include <Callback.h>

Public Types
using	Callback = std::function<void(Args...)>
	Signature of the wrapped callback.

Public Member Functions
	OnceCallback (Callback callback)
	Wraps a callback.
bool	invoke (Args... args)
	Calls the wrapped callback, unless it has already been called.
bool	was_invoked () const
	Reports whether the callback has run.

Detailed Description

template<typename... Args>
class stripekit::OnceCallback< Args >

Makes a callback safe to hand to code that might fire it more than once.

StripeKit's callback-form methods must invoke their completion exactly once: calling it twice corrupts whatever is waiting on it, and never calling it hangs the request. Adapters wrap the completion in one of these so the rule holds even on unusual error paths.

auto once = std::make_shared<stripekit::OnceCallback<Result>>(std::move(completion));
transport.send(request, [once](Result result) { once->invoke(std::move(result)); });

Safe to call from several threads at once.

Template Parameters

Args	Argument types the wrapped callback takes.

See also

Writing an Adapter

Definition at line 40 of file Callback.h.

Member Typedef Documentation

Callback

template<typename... Args>

using stripekit::OnceCallback< Args >::Callback = std::function<void(Args...)>

Signature of the wrapped callback.

Definition at line 43 of file Callback.h.

Constructor & Destructor Documentation

OnceCallback()

template<typename... Args>

stripekit::OnceCallback< Args >::OnceCallback ( Callback callback )

inlineexplicit

Wraps a callback.

Parameters

callback

The callback to guard. May be empty, in which case invoke() still reports the first call but does nothing.

Definition at line 51 of file Callback.h.

Member Function Documentation

invoke()

template<typename... Args>

bool stripekit::OnceCallback< Args >::invoke ( Args... args )

inline

Calls the wrapped callback, unless it has already been called.

Parameters

args	Arguments forwarded to the callback.

Returns

True if this call ran the callback; false if it had already run, in which case the arguments are discarded.

Definition at line 60 of file Callback.h.

was_invoked()

template<typename... Args>

bool stripekit::OnceCallback< Args >::was_invoked ( ) const

inline

Reports whether the callback has run.

Returns

True once invoke() has been called.

Definition at line 83 of file Callback.h.

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The documentation for this class was generated from the following file:

• include/StripeKit/Callback.h