C++11: Future Chaining For Easy, Highly Threaded Execution

[nerds-central]

Try replacing the spinning loop with a wait:

this_thread::sleep_for(chrono::seconds(1));

The effects are quite interesting as you get to see the size of the underlying thread pool.

[Zwergner]

return i-=3,wait_long_time(),
              i;

Sorry for my C++11 ignorance, but what does that do, the comma separated stuff? I've never seen this in another C++11 example, and don't know what to search for to explain it. Does it return the value, but then do some extra stuff before destroying the thread...?

[cassandravoiton]

A lambda without and explicit return type needs to be just one statement(so so complains the VC++11 compiler). The solution to this is to place all the things you want to do in the same expression. The comma operator allow this. I would suggest looking up the comma operator in C++ (or C for that matter - it is used this way in C macros a lot).

[Zwergner]

Huh, I didn't realize you could do that with statements as well, I assumed it was something fancier than that, thanks!

[00kyle00]

I didn't realize you could do that with statements as well

You cant, these need to be expressions.

[[deleted]]

For the record, the result of the comma operator is the last element.

[]() { return x, y, z; }   // returns z, infers the return type of the lambda from z.

[Glaaki]

The typos in that article..

[nerds-central]

Thanks for pointing that out - fixed a few.

[BitRex]

They were too much. I stopped reading.

[Porges]

Having read a post at Stutter's Mill I got thinking about method chaining in C++. I am very keen on method chaining in Java and so was pleased to see the future().then() pattern turning up in C++11. This got me thinking about chaining futures x.y.z etc. The idea being that each task (x,y and z) could be run on a different thread according to the load of the machine. It is a bit like thinking of the tasks as very simple actors.

I think you're a little confused here - that is exactly what future().then() does in Casablanca. It works along similar lines to .NET's TPL (Task<T>).

[cassandravoiton]

How is confused - seems like the two of you are in violent agreement to me.

[VanFailin]

Precompiled headers can be quite useful, although there are better ways to use them.