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C++ and the Google Summer of Code

By Meeting C++ | Mar 1, 2014 02:44 PM | Tags: gsoc c++14 c++11 boost basics

I wrote an overview over this years Google Summer of Code and C++

C++ and the Google Summer of Code

by Jens Weller

From the Article:

During the last few weeks I got interested in the Google Summer of Code (GSoC), as I did read some emails on the boost mailing lists about it. The Google Summer of Code is for a lot of open source projects an important opportunity to improve and extend their code base, and in 2014 it happens for the 10th time!

C++ Now 2014 sold out in under a month

By Blog Staff | Feb 9, 2014 08:40 PM | Tags: intermediate basics advanced

cppnow14-soldout.pngAs interest in C++ keeps rising, there are more C++ events but they are also selling out faster. C++ Now 2013, Going Native 2013, and C++ and Beyond 2013 all sold out, some six months before the event.

Now C++ Now 2014 has sold out faster than last year -- this time it sold out in less than a month since registration opened, with over three months left to go.

The good news: You can still register to get on the waiting list, and if you act now there's a good chance you can still get a seat. Each year there will be some number of cancellations, and the organizers expect to be able to take a number of people on the waiting list.

If you have not yet registered for C++ Now 2014 but are interested in potentially going, even if you're not certain yet you should join the waiting list today to get in the queue for a chance to sign up for the last few seats that will open up!

 

If you missed registering for C++ Now and don't make the waiting list, don't despair -- there will be additional major C++ events around the world later this year. Watch for upcoming announcements here on isocpp.org. Stay tuned...

Quick Q: What do braces mean as a function argument? -- StackOverflow

By Blog Staff | Feb 5, 2014 03:12 AM | Tags: basics

Quick A: Something cool and convenient -- you can construct a temporary variable of the parameter type without having to repeat the type.

From SO:

C++ 11 Curly Braces

I haven't used C++ for a good few years, and have just come across this:

program.build({ default_device })

The definition is:

cl_int build(
    const VECTOR_CLASS<Device>& devices,
    const char* options = NULL,
    void (CL_CALLBACK * notifyFptr)(cl_program, void *) = NULL,
    void* data = NULL) const

What are the curly braces there for? I have never seen them used in a function call like this before. I assume it has something to do with the function pointer, but that seems optional?

C++ User Group Meetings in February

By Meeting C++ | Jan 31, 2014 04:34 AM | Tags: community basics

February will be a month full of C++ user group meetings:

C++ User Group Meetings in February

by Jens Weller

From the article:

There are a few new user groups, some of them even will meet in February for the first time. There is now a russian C++ users group organizing Meetings in St. Peterburg and Moscow. In Germany, the C++ user group Munich has met in January for the first time, with over 50 people attending the first meeting. In February the user groups of Aachen and Dortmund will meet for the first time. And, already meeting last year for the first time, there is now a dutch C++ user group!

Quick Q: Is pass-by-value-and-then-move a bad idiom? -- StackOverflow

By Blog Staff | Jan 13, 2014 01:47 AM | Tags: basics

Quick A: It's a good style by default when you know you'll keep a copy of the parameter anyway. If you have an expensive-to-move type or otherwise want additional control, you can overload on &/&& or else perfect-forward.

Recently on SO:

Is the pass-by-value-and-then-move construct a bad idiom?

Since we have move semantincs in C++, nowadays it is usual to do

void set_a(A a) { _a = std::move(a); }

The reasoning is that if a is an rvalue, the copy will be elided and there will be just one move.

But what happens if a is an lvalue? It seems there will be a copy construction and then a move assignment (assuming A has a proper move assignment operator). Move assignments can be costly if the object has too many member variables.

On the other hand, if we do

void set_a(const A& a) { _a = a; }

There will be just one copy assignment. Can we say this way is preferred over the pass-by-value idiom if we will pass lvalues?

Quick Q: Why prefer making shared_ptrs via make_shared? -- StackOverflow

By Blog Staff | Jan 10, 2014 12:47 PM | Tags: basics

Quick A: Because it's more efficient, since it can eliminate an additional allocation.

Recently on SO:

Difference in make_shared and normal shared_ptr in C++

std::shared_ptr<Object> p1 = std::make_shared<Object>("foo");
std::shared_ptr<Object> p2(new Object("foo"));

Many google and stackoverflow posts are there on this, but I am not able to understand why make_shared is more efficient than directly using shared_ptr. Can someone explain me step by step sequence of objects created and operations done by both so that I will be able to understand how make_shared is efficient. I have given one example above for reference.