: Standard C++

class IApp;

class Component
{
    IApp* app;
    template<typename T>
    void registerEvent(const int& evtId, Status (T::*func) (int));
};

class IApp : public Component {
  ...
};

template <typename T>
Component::registerEvent(const int& evtId, Status (T::*func) (int)) {
  auto res = std::bind(func, (T*)this, std::placeholders::_1);
  app->registerForEvent(evtId);
}

If need be, also define A::registerEvent after Component::registerEvent.

Quick Q: Why is list initialization (using curly braces) better than the alternatives?

By Adrien Hamelin | May 16, 2016 01:31 PM | Tags: c++11 basics

Quick A: It is less likely to generate an unexpected error.

Recently on SO:

Why is list initialization (using curly braces) better than the alternatives?

Basically copying and pasting from Bjarne Stroustrup's "The C++ Programming Language 4th Edition":

List initialization does not allow narrowing (§iso.8.5.4). That is:

An integer cannot be converted to another integer that cannot hold its value. For example, char to int is allowed, but not int to char.

A floating-point value cannot be converted to another floating-point type that cannot hold its value. For example, float to double is allowed, but not double to float.

A floating-point value cannot be converted to an integer type.

An integer value cannot be converted to a floating-point type.

Example:
void fun(double val, int val2) {

    int x2 = val; // if val==7.9, x2 becomes 7 (bad)

    char c2 = val2; // if val2==1025, c2 becomes 1 (bad)

    int x3 {val}; // error: possible truncation (good)

    char c3 {val2}; // error: possible narrowing (good)

    char c4 {24}; // OK: 24 can be represented exactly as a char (good)

    char c5 {264}; // error (assuming 8-bit chars): 264 cannot be
                   // represented as a char (good)

    int x4 {2.0}; // error: no double to int value conversion (good)

}
The only situation where = is preferred over {} is when using auto keyword to get the type determined by the initializer.

Example:
auto z1 {99}; // z1 is an initializer_list<int>
auto z2 = 99; // z2 is an int
Conclusion

Prefer {} initialization over alternatives unless you have a strong reason not to.

CppCon 2015 Expression Templates - Past, Present, Future--Joel Falcou

By Adrien Hamelin | May 16, 2016 01:21 PM | Tags: efficiency advanced

Have you registered for CppCon 2016 in September? Don’t delay – Early Bird registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Expression Templates - Past, Present, Future+

by Joel Falcou

Part 1: (watch on YouTube) (watch on Channel 9)

Part 2: (watch on YouTube) (watch on Channel 9)

Part 3: (watch on YouTube) (watch on Channel 9)

Summary of the talk:

Expression Templates is one of this C++ idiom people learn to either love or hate. The main issues with ET is that everubody has its own conception about what they are, when they should be used, what benefits they give and what are their trade off. For a long time, Expression Tempaltes has been seen has a way to improve temporary heavy code. If the seminal implementation of ET by Todd Veldhuizen was actually about this, the landscape has changed since C++11 and C++14.

This workshop will go over : - what are exactly Expression Templates and what kind of use case they can solve elegantly and efficiently - what are the benefits that one may reap by using expression tempalte in its library - what are the real cost of expressont empaltes both at runtime and compile-time - which tools to use to not reinvent the tempalte wheel everytime including an introduction to Boost.PROTO an Boost.HANA.

The main objective is to clarify why, even in C++1*, this idiom has a meaningful set of applications and how to navigate around its pitfalls.

Top 10 dumb mistakes to avoid with C++ 11 smart pointers -- Deb Haldar

By Mantosh Kumar | May 15, 2016 10:36 PM | Tags: intermediate

Discussion on various aspect of C++11 smart pointers uses.

Top 10 dumb mistakes to avoid with C++ 11 smart pointers

by Deb Haldar

From the article:

I love the new C++ 11 smart pointers. In many ways, they were a godsent for many folks who hate managing their own memory. In my opinion, it made teaching C++ to newcomers much easier.

However, in the two plus years that I've been using them extensively, I've come across multiple cases where improper use of the C++ 11 smart pointers made the program inefficient or simply crash and burn. I've catalogued them below for easy reference.

CppCon 2015 Implementation of a component-based entity system in modern C++--Vittorio Romeo

By Adrien Hamelin | May 13, 2016 02:17 PM | Tags: performance efficiency c++14

Have you registered for CppCon 2016 in September? Don’t delay – Early Bird registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Implementation of a component-based entity system in modern C++

by Vittorio Romeo

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

An alternative to deep inheritance trees for game and application architecture design is "composition". Separating data (in independent components) from logic (in independent systems) allows the code to be more reusable and more efficient, alongside additional benefits. Using modern C++11 and C++14 features, it is possible to design an efficient and user-friendly component-based entity system library, with intuitive syntax and convenient cost-free abstractions.

boost 1.61.0 released

By Felix Petriconi | May 13, 2016 06:48 AM | Tags: boost

The boost community has released their library in version 1.61.0.

boost 1.61.0 released

by the boost organization

From the release note:

Beside many bug fixes and enhancements in the existing libraries, these new libraries were added:

New Libraries

Compute:
Parallel/GPU-computing library

DLL:
Library for comfortable work with DLL and DSO. Library provides a portable across platforms way to:

load libraries

import any native functions and variables

make alias names for C++ mangled functions and symbols

query libraries for sections and exported symbols

self loading and self querying

getting program and module location by exported symbol

Hana:
A modern C++ metaprogramming library. It provides high level algorithms to manipulate heterogeneous sequences, allows writing type-level computations with a natural syntax, provides tools to introspect user-defined types and much more.

Metaparse:
A library for generating compile time parsers parsing embedded DSL code as part of the C++ compilation process. The library is similar to Spirit, however while parsers built with Spirit parse at run-time, parsers built with Metaparse parse at compile-time.

CppCon 2015 Ranges for the Standard Library--Eric Niebler

By Adrien Hamelin | May 11, 2016 01:03 PM | Tags: intermediate experimental

Have you registered for CppCon 2016 in September? Don’t delay – Early Bird registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Ranges for the Standard Library

by Eric Niebler

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

Range-based interfaces are functional and composable, and lead to code that is correct by construction. With concepts and ranges coming to the STL, big changes are in store for the Standard Library and for the style of idiomatic C++. The effort to redefine the Standard Library is picking up pace. Come hear about one potential future of the STL from one of the key people driving the change.

CppCon 2015 Tuning C++: Benchmarks, and CPUs, and Compilers! Oh My!--Chandler Carruth

By Adrien Hamelin | May 9, 2016 01:24 PM | Tags: performance advanced

Have you registered for CppCon 2016 in September? Don’t delay – Early Bird registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Tuning C++: Benchmarks, and CPUs, and Compilers! Oh My!

by Chandler Carruth

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

A primary use case for C++ is low latency, low overhead, high performance code. But C++ does not give you these things for free, it gives you the tools to control these things and achieve them where needed. How do you realize this potential of the language? How do you tune your C++ code and achieve the necessary performance metrics?

This talk will walk through the process of tuning C++ code from benchmarking to performance analysis. It will focus on small scale performance problems ranging from loop kernels to data structures and algorithms. It will show you how to write benchmarks that effectively measure different aspects of performance even in the face of advanced compiler optimizations and bedeviling modern CPUs. It will also show how to analyze the performance of your benchmark, understand its behavior as well as the CPUs behavior, and use a wide array of tools available to isolate and pinpoint performance problems. The tools and some processor details will be Linux and x86 specific, but the techniques and concepts should be broadly applicable.

Quick Q: Is this std::ref behaviour logical?

By Adrien Hamelin | May 9, 2016 01:19 PM | Tags: intermediate c++11

Quick A: Yes, std::ref can be reassigned (see example)

Recently on SO:

Is this std::ref behaviour logical?

A small modification to f2 provides the clue:
template<class T>
void f2(T arg)
{
    arg.get() = xx;
}
This now does what you expect.

This has happened because std::ref returns a std::reference_wrapper<> object. The assignment operator of which rebinds the wrapper. (see http://en.cppreference.com/w/cpp/utility/functional/reference_wrapper/operator%3D)

It does not make an assignment to the wrapped reference.

In the f1 case, all is working as you expected because a std::reference_wrapper<T> provides a conversion operator to T&, which will bind to the implicit right hand side of ints implicit operator+.