#2782

C++Ox, Lambdas and Lots of Brackets

The p&p dev team today had a random C++ moment (don’t worry it doesn’t happen often).

I’ve been playing around with C++, writing samples for “Parallel Programming with Microsoft Visual C++” and am a big fan of the new C++0x lambda syntax. It does however make heavy use of brackets. The following is legal code.

auto f = [](){};

Which defines an empty lamba, f, that has an empty capture list and takes no parameters.

There’s more on the C++Ox lambda syntax here. The bit I really like is being able to specify what get’s captured and how. For example the following captures r by reference and b by value:

int r = 0;
int b = 2;
auto f = [&r, b]() { r = b * b; }
f();

int r = 0;
int b = 2;
auto f = [&]() { r = b * b; }
f();

Typically you’re better off being more specific about what you’re capturing and how. [&] is great for demos but I tend to avoid it in real code.

The samples for the C++ book make extensive use of lambdas because the Parallel Patterns Library does.