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// In this example, the thread isn't launched at once...
future<int> x(&my_calculating_function,
   futures::lazy_evaluation);
 
// ... but only when the future is actually used.
int y = 3.1415 * x;

Lazy evaluation can be useful if you’re not too sure whether or not you’ll use the value after all.

Finally, using a future may result in an exception being thrown.

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// If the background thread throws an exception, that's
// caught, and (if possible) wrapped into a new
// futures::exception.
future<int> x(&throwing_function);
 
// The new futures::exception would be thrown here.
int y = 3.1415 * x;

And that’s all there is to it. Hope you enjoy the future!

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This entry was posted on Tuesday, April 21st, 2009 at 10:43 pm by unwesen and is filed under features. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.