Inheriting Constructors in C++11 -- 741MHz

By Blog Staff | Jul 23, 2014 04:53 AM | Tags: basics

Following up on Monday's linked article:

Inheriting Constructors in C++11

by 741MHz

From the article:

Delegating Constructors [... are] extremely useful in boosting efficiency, [but] it does not solve the problem when programmer wants to create a derived class that has exactly the same set of constructor as its base class or classes. In which case programmers are forced to tediously duplicate constructors of the base class...

C++11 solves this problem by introducing constructor inheritance. In a derived class, programmers can write a single using T::T; statement that makes a derived class automatically inherit constructors of a base class. For example: ...

Delegating Constructors in C++11 -- 741MHz

By Blog Staff | Jul 21, 2014 04:52 AM | Tags: basics

In case you missed it on 741MHz:

Delegating Constructors in C++11

by 741MHz

From the article:

C++ has caught up with other popular object-oriented languages such as Scala, Java, C# and others when it comes to constructor delegation, a feature that is now supported as per 2011 core language specification of ISO C++. This solves a common problem with repetitive coding, which is tedious and fragile, that C++ programmers had to do in order to provide multiple class constructors.

...

C++11 allows that a constructor of a class type “A” may have an initializer list that invokes another constructor of the same type. Therefore, programmers can get rid of undesirable common initialization function and duplicate all at once by writing the code like this: ...

Making the Most of C++11/14 -- Sasha Goldshtein

By Blog Staff | Jul 10, 2014 07:23 PM | Tags: c++14 c++11 basics

New on Lanyrd:

Making the Most of C++11/14 (slides)

by Sasha Goldshtein

The C++11 standard is already behind us, and C++14 is just around the corner. With a huge variety of language features such as lambdas, rvalue references, auto and decltype, and variadic templates, it's easy to get lost in C++. In fact, it often seems like a completely new and foreign language. In this workshop we will look at the most important language features that improve system performance and developer productivity, with a glimpse towards what C++14 will bring. We will make the most of Visual C++ 2013 and see how to convert and refactor code to use modern C++ idioms.

C++11 Final Override -- 741MHz

By Blog Staff | Jul 8, 2014 10:39 PM | Tags: intermediate basics

A good article posted last year and making the rounds again this week:

C++11 Final Override

by 741MHz

From the article:

C++11 introduces two important keywords in relation to polymorphism and inheritance — the override and final. Using those keywords should become a habit of any C++ developer. It is worth using every time except when writing a base class. This will make the code clear, maintainable, and potentially save hours that would have been otherwise wasted chasing an error in debugger.

Quick Q: Is vector storage contiguous? -- Stack Overflow

By Blog Staff | Jun 30, 2014 09:50 AM | Tags: basics

Quick A: Yes.

Recently on SO:

std::vector: contiguous data and copy/move

I have two questions for the following code: 1) Will the elements of faces be contiguous? 2) Does std::vector copy or move Face f when inserting it?

#include <vector>   
int main()
{
    struct Face {};
    std::vector<Face> faces;

    for (int i=0; i<10; ++i)
    {
        Face f;

        faces.push_back (f);
    }

    return 0;
}

Why C++ Sails When the Vasa Sank -- Scott Meyers

By Blog Staff | Jun 23, 2014 10:24 AM | Tags: intermediate basics

Now available online, a nice talk by Scott Meyers about why modern C++ is alive and continues to enjoy life and growth:

Why C++ Sails When the Vasa Sank

by Scott Meyers

The Vasa was a 17th-century Swedish warship which suffered such feature creep during construction that it sank shortly after leaving the harbour on its maiden voyage. In the early 1990s, the C++ standardisation committee adopted the Vasa as a cautionary tale, discouraging prospective language extensions with "Remember the Vasa!" Yet C++ continued to grow, and by the time C++ was standardised, its complexity made the Vasa look like a rowboat.

The Vasa sank, however, while C++ cruised, and it looks likely to continue doing so even as the latest revised standards (C++11 and C++14) add dozens of new features, each with its own idiosyncrasies. Clearly, C++ has gotten some important things right. In this talk, Scott Meyers considers the lessons to be learned from the ongoing success of a complex programming language that's over 30 years old, yet very much alive and kicking.

Quick Q: Is unique_ptr guaranteed to store nullptr after move? -- StackOverflow

By Blog Staff | Jun 13, 2014 03:10 AM | Tags: basics

Quick A: Yes. Otherwise, it would be unsafe and a lot less unique.

From SO:

Is unique_ptr guaranteed to store nullptr after move?

std::unique_ptr<int> p1{new int{23}};
std::unique_ptr<int> p2{std::move(p1)};
assert(!p1); // is this always true?

Ref-qualified member functions -- Alexander Kulikov

By Blog Staff | May 28, 2014 07:23 PM | Tags: intermediate basics

Today on Kukuruku:

Ref-qualified member functions

by Alexander Kulikov

From the article:

Today I’m going to tell you about a new and a little known (to my mind) C++ feature — reference-qualified member functions. I’ll tell about the rules of such functions overloading and, as an example of use, I’ll show you that with the help of ref-qualified you can try to improve the resource management scheme, which is implemented with the help of another C++ idiom — RAII.

Quick Q: Why can't a data member be in a lamba capture list -- StackOverflow

By Blog Staff | May 22, 2014 12:01 PM | Tags: basics

Quick A: Because you can only capture local (stack) objects, including function parameters, and to access a data member in a member function you capture the local variable this.

Today on SO:

Why can't a data member be in a lamba capture list

I have a class foo that has bar as a member variable.

In another member function of the class, I'm writing a lambda function:

[bar](void){}

But I can't include bar in the capture list. Why is that?

Quick Q: How do generic lambdas work? -- StackOverflow

By Blog Staff | May 12, 2014 08:31 AM | Tags: basics

Quick A: They generate a templated operator(), and that means you can call the same closure object with all sorts of different parameters and it just stamps out the function for each set of parameter types.

A "new classic" question on SO, classic because it was posted a year ago, but newly relevant because now the mainstream compilers are implementing the feature:

How does generic lambda work in C++14?

How does generic lambda work (auto keyword as argument type)?

Is it similar to templates where for each different argument type compiler generates functions with the same body but changed types or is it more similar to Java's generics?

Code example:

auto glambda = [](auto a) { return a; };