SFINAE std::result_of? Yeah, right!

by Scott Prager

Return type deduction pre-decltype and auto could really make one mad. Back then, if you wanted a function object, you had to make it "adaptable", meaning it had to inherit from std::unary_ or binary_function and define its first_argument_type, second_argument_type, and result_type. There had been no concept of "transparent functors" allowing us to pass polymorphic functions to higher order functions (like std::plus<> to std::accumulate). For an example of programming in these dark ages, check out the FC++ FAQ.

Using C++ on Mission and Safety Critical Platforms

by Bill Emshoff

(watch on YouTube) (watch on Channel 9)

The Joint Strike Fighter (JSF) is the first major DOD aircraft program to use C++. Much of this software is either safety critical or mission critical and so must be written in such a way as to be clear, readable, unambiguous, testable, and maintainable. We discuss the driving requirements behind the standard and its evolution. We give a quick overview of our standard and discuss how it differs from later standards such as MISRA C++. We discuss lessons learned over our nine year history of applying the standard to a large embedded software program. We also address ambiguities in rules and difficulties with automated checking of conformance with the standard.

All videos of Meeting C++ 2014 are online!

by Jens Weller

I uploaded yesterday the last video of last years Meeting C++ conference! So you can now watch all 21 talks and the 2 keynotes at youtube!

Type Deduction and Why You Care

by Scott Meyers

(watch on YouTube) (watch on Channel 9)

C++98 had template type deduction, and it worked so intuitively, there was little need to understand what took place under the covers. C++11 extends type deduction to include universal references, applies it to auto variables and lambda expressions, then throws in a special auto-only deduction rule. C++14 pushes the boundary further, adding two forms of function return type deduction (auto and decltype(auto)) for arbitrary functions and offering auto parameters for lambdas. The result is that what could be treated as a black box in C++98 has become a topic that practicing C++ developers really need to understand. This talk will give you the information you need to do that.

Iterators++, Pat 2

This is the third in a series about proxy iterators, the limitations of the existing STL iterator concept hierarchy, and what could be done about it. In the first post I explained what proxy iterators are (an iterator like vector<bool>‘s that, when dereferenced, returns a proxy object rather than a real reference) and three specific difficulties they cause in today’s STL:

1. What, if anything, can we say in general about the relationship between an iterator’s value type and its reference type?
2. How do we constrain higher-order algorithms like for_each and find_if that take functions that operate on a sequence’s elements?
3. How do we implement algorithms that must swap and move elements around, like sort and reverse?

GCC5 and the C++11 ABI

by rhjason

The GNU C++ team works hard to avoid breaking ABI compatibility between releases, including between different -std= modes. But some new complexity requirements in the C++11 standard require ABI changes to several standard library classes to satisfy, most notably to std::basic_string and std::list. And since std::basic_string is used widely, much of the standard library is affected...

Expressions can have Reference Type

by Scott Meyers

Today I got email about some information in Effective Modern C++. The email included the statement, "An expression never has reference type." This is easily shown to be incorrect, but people assert it to me often enough that I'm writing this blog entry so that I can refer people to it in the future...

Compile-Time and Runtime-Safe Replacement for “printf”

by Sasha Goldshtein

C++ 11 is truly beautiful. And one of the ways in which it is beautiful is how you can implement a compile-time and runtime-safe version of the popular C runtime function printf...

Iterators++, Part 1

by Eric Niebler

In the last post, I described the so-called proxy iterator problem: the fact that iterators that return proxy references instead of real references don’t sit comfortably within the STL’s framework. Real, interesting, and useful iterators fall foul of this line, iterators like vector<bool>‘s or like the iterator of the zip view I presented. In this post, I investigate what we could do to bring proxy iterators into the fold — what it means for both the iterator concepts and for the algorithms. Since I’m a library guy, I restrict myself to talking about pure library changes...

Improving error messages in C++ by transporting substitution failures

by Paul Fultz II

This is an advanced blog post more geared to library writers who want to improve error messages due to substitution failure. It discuss how substitution failures can be transported so the correct information can be presented to the user. Lets first look at the problem...