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Stroustrup Reveals What's New In C++ 11
snydeq writes "Bjarne Stroustrup discusses the latest version of C++, which, although not a major overhaul, offers many small upgrades to appeal to different areas of development. From the interview: 'I like the way move semantics will simplify the way we return large data structures from functions and improve the performance of standard-library types, such as string and vector. People in high-performance areas will appreciate the massive increase in the power of constant expressions (constexpr). Users of the standard library (and some GUI libraries) will probably find lambda expressions the most prominent feature. Everybody will use smaller new features, such as auto (deduce a variable's type from its initializer) and the range-for loop, to simplify code.'"
I've been using the C++11 for 6 months now in my own project (libbitcoin) and the new features and syntax really make your code sharper, clearer and better. C++ is no longer that unsafe language if you know how to code in it properly - you never really have to do any manual memory management if you use shared pointers.
constexpr allowed me to create compile time constants that are the function of a bunch of complicated expressions. Sure, I could just put the result in the code, but by using constexpr (a far more expressive metaprogramming utility than templates) I can document where those constants came from by using code. Neat huh!
Using variadic templates, I was able to write decorators that can be applied to any function. I simply wrap my functions with this class and then its operator() will be called before calling the passed in function object (which I can define using lambdas or std::bind now :)
auto means I no longer have to type std::vector>::iterator in every for loop. Likewise for (const transaction& tx: block.transactions) is much more terse and clearer.
The new features to the standard library are brilliant. Threading has never been easier: std::thread t(foo, x, y); will call foo(x, y) in a new thread. When I decide to finish the threads and then join them I call: t.join(); ... Simple.
As libbitcoin is highly asynchronous, I don't like to use exceptions (which thread does it originate in? where does it get caught? .etc). C++11 now provides the header which defines std::error_code(). An error_code object can be tested as a boolean (to see whether the error is set or not) or compared against an enum value (which you define). They also have an error message (which if you defined the enum value it is set to, you can also set the message), and also you can group different error code values into broader categories! Really useful for asynchronous programming.
std::atomic for a thread-safe counter (useful when you have multiple thread paths executing and want to see when they all finished - increment your counter by one after each path completes) and std::atomic for a thread-safe flag. ... That's off the top of my head. There are dozens of many small things like this. C++ was always my 'native' language, but now it's truly my home.
Now be careful, because inheritance was not really intended for code reuse. If it does help with code reuse, that's a positive consequence, but it's not what inheritance is for, first and foremost. See Liskov substitution principle and all that jazz.
A successful API design takes a mixture of software design and pedagogy.
Mainstream use is shifting back to C++ since Microsoft decided that C++ was batter than C# (or at least Sinofsky and the Windows team decided that was the case). Herb Sutter has done a lot of presentations on the new paradigm at Microsoft - do a quick google.
Of particular note is the reason they're giving for this: in the datacentre native code reduces the amount of energy required to run your apps, and that adds up significantly if you're using dynamic or even JIT language.