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Lambdas vs. Closures -- Scott Meyers

By Blog Staff | May 22, 2013 08:34 PM | Tags: basics

This bears repeating:

Lambdas vs. Closures

by Scott Meyers

From the article:

In recent days, I've twice found myself explaining the difference between lambdas and closures in C++11, so I figured it was time to write it up. ...

GotW #5 Solution: Overriding Virtual Functions -- Herb Sutter

By Blog Staff | May 22, 2013 05:29 PM | Tags: None

The solution to GotW #5 is now available:

GotW #5 Solution: Overriding Virtual Functions (updated for C ++11/14)

by Herb Sutter

From the article:

Exactly one of the following can be true for a polymorphic type:

  • Either destruction via a pointer to base is allowed, in which case the function has to be public and had better be virtual;
  • or else it isn’t, in which case the function has to be protected (private is not allowed because the derived destructor must be able to invoke the base destructor) and would naturally also be nonvirtual (when the derived destructor invokes the base destructor, it does so nonvirtually whether declared virtual or not).

C++Now 2013 Trip Report -- Jens Weller

By Blog Staff | May 20, 2013 01:54 PM | Tags: None

Reporting from the just-concluded C++Now 2013 event:

C++ Now 2013 -- Trip Report

by Jens Weller

From the article:

This years sessions focused a lot on threading, which brought great talks about atomics, transactional memory or C++11 threading to the conference. I have to admit, that threading is not my main interest in C++, so not all of those talks were meant for me. But having three tracks always gives you a great choice. And also gave me the confidence that the decision to go for 3 tracks at this years Meeting C++ conference was right.

GotW #4 Solution: Class Mechanics -- Herb Sutter

By Blog Staff | May 20, 2013 12:45 PM | Tags: intermediate basics

The solution to GotW #4 is now available:

GotW #4 Solution: Class Mechanics (updated for C++11/14)

by Herb Sutter

From the article:

... To see why, consider the following canonical forms for how operator+= and operator+ should normally be implemented for some type T. 
T& T::operator+=( const T& other ) {
    //...
    return *this;
}

 

T operator+( T a, const T& b ) {
    a += b;
    return a;
}

Did you notice that one parameter is passed by value, and one by reference? That’s because if you’re going to copy from a parameter anyway, it’s often better to pass it by value, which will naturally enable a move operation if the caller passes a temporary object such as in expressions like (val1 * val2) + val3. We’ll see more on parameter passing in a future GotW. ...

.

GotW #3 Solution: Using the Standard Library (or, Temporaries Revisited) -- Herb Sutter

By Blog Staff | May 16, 2013 01:11 PM | Tags: intermediate basics

The solution to GotW #3 is now available:

GotW #3 Solution: Using the Standard Library (or, Temporaries Revisited) (updated for C++11/14)

by Herb Sutter

From the article:

With no other changes, simply using the standard find algorithm could do everything the range-based for loop did to avoid needless temporaries (and questions about them) [...] and it further increases our level of abstraction.

C++14 Committee Draft (CD) Published at isocpp.org -- Michael Wong

By MichaelWong | May 16, 2013 11:21 AM | Tags: None

[Ed.: Thanks to Michael Wong for sharing his commentary and perspective on the C++14 CD while on the scene at the C++Now conference. Posted at the IBM C/C++ Cafe blog.]

C++14 Committee Draft (CD) published at isocpp.org

C++14 Committee Draft is here and can be accessed at isocpp.org. This is in keeping with the practice of greater transparency ... [and] was also announced to the C++NOW crowd by Jens Weller at the Community evening session last night.

 

The C++ Programming Language Fourth Edition is now shipping

By Bjarne Stroustrup | May 13, 2013 10:27 AM | Tags: None

My book The C++ Programming Language (Fourth Edition) is now shipping.

I got my copy (the very first copy!) on Friday. At 9am Monday, it became available on the publisher’s site, InformIT, and at 10am it had sold out. This is all very scary for an author. I have worked hard on this for about four years (not counting the 13 years it took getting the C++11 standard out), but of course a 1360-page book is huge, so I’ll find flaws. Anyway, that’s my problem.

For a description of the book, see http://www.stroustrup.com/4th.html. In particular, read the preface and the back-cover text to see if this book might be of interest to you. It aims to be the most comprehensive description of the C++ language, standard library, and the programming techniques C++ is designed to support. It is not meant to be the quickest introduction to C++11 or a first introduction to programming. My TC++PL4 web page also has an extended table of contents, the Tour of C++, and the exercises.

As ever, comments (preferably polite and constructive) and bug reports are most welcome.

GotW #2 Solution: Temporary Objects -- Herb Sutter

By Blog Staff | May 13, 2013 05:27 AM | Tags: intermediate basics

The solution to GotW #2 is now available:

GotW #2 Solution: Temporary Objects (updated for C++11/14)

by Herb Sutter

From the article:

Because C++ naturally enables move semantics for returned values like this string object, there’s usually little to be gained by trying to avoid the temporary when you return by value. ... For example, if the caller writes auto address = find_addr( mylist, “Marvin the Robot” );, there will be at most a cheap move (not a deep copy) of the returned temporary into address, and compilers are allowed to optimize away even that cheap move and construct the result into address directly.

But what if you did feel tempted to try to avoid a temporary in all return cases by returning a string& instead of string? Here’s one way you might try doing it that avoids the pitfall of returning a dangling reference to a local or temporary object: [...] To demonstrate why this is brittle, here’s an extra question:

For the above function, write the documentation for how long the returned reference is valid.

Go ahead, we’ll wait. ...

The questions for #3 are posted for discussion:

GotW #3: Using the Standard Library (or, Temporaries Revisited)