Re: [boost] Review Request: future library (N2561/Williams version)

From: Peter Dimov (pdimov_at_[hidden])
Date: 2008-05-08 09:45:27

vicente.botet:
>>> I don't understand the need of this function. Could you show a use case
>>> for promise::get_future() function?
>>
>> promise::get_future() is the only way to get a future from a promise.
>> Since the whole point of using promise is to get the future, it's rather
>> pointless without it.
>
> why this is not an internal feautre?

You have to have a way to create the initial future, but for the "one time" 
semantics one can have for example

    promise::promise( future& f );

instead of get_future.

FWIW, Braddock has argued (see the archives) that it's convenient to be able 
to obtain a future from a promise, without the "one time" restriction. 
("His" futures are "shared" though, as are "mine".) I argued that without 
this feature, a promise can detect that no futures are left and can cancel 
its task.