7. (C++11 Promises 101)

A promise is the counterpart of a future. Both are able to temporarily hold a shared state. Thus, a promise is a general mechanism to allow values and exceptions to be passed out of threads. A promise is the ‘push’ end of the promise–future communication channel.

Answer the following questions:

a) Create a default promise, a promise with an empty shared state and a promise based on the move constructor.

b) Create a promise with double as stored value. Then create a future that is associated with the promise.

c) Start a thread with the new future from part b). Create a thread function that uses the value of the shared data.

d) Use the promise to set the value of the shared data.