In C++11, no – there’s no penalty. I would even consider it a very good style to not pollute any “more visible” scopes with you implementation details, unless, of course, you want to reuse that functor elsewhere. However, lambdas are essentially a condensed form of this idea, and should usually be preferred if you are … Read more
This would probably interest you, but here is a short version: When you assemble the .cpp, .c or whatever files, each translation unit (that is, each file) generates an object file. When creating the final executable, you combine all the object files into a single binary. For static libraries, you compile the static archive (.a … Read more
std::function<int(int)> bar = std::bind(foo, 2, std::placeholders::_1);
According to this bugreport, install(TARGETS) command flow accepts only targets created within the same directory. So you need either move the add_library() call into the top-level directory, or split install(TARGETS) call into per-target ones, and move each of them into the corresponding subdirectory. Since CMake 3.13 install(TARGETS) can work even with targets created in other … Read more
Main reason : To keep compatibility with the existing code, since they have done it with C also. Also have a look at these C++ Coding standards, which presents some generic reasoning regarding the importance of convention. These links discusses about the naming conventions of C/C++ Standard Library. Naming Convention for C API C/C++ Library … Read more
Unfortunately, std::array does not have an initializer list constructor. Indeed, it has no user-defined constructor whatsoever — this “feature” is a leftover from C++03 where omitting all user-defined constructors was the only way to enable the C-style brace initialization. It is IMHO a defect in the current standard. So why doesn’t built-in brace initialization work … Read more
[…] will the compiler be able to optimize away the extra initializations? In almost all cases: yes. Should I always write my move constructors by calling the move assignment operator? Yes, just implement it via move assignment operator, except in the cases where you measured that it leads to suboptimal performance. Today’s optimizer do an … Read more
For one, the functor can contain internal state; a state that is valid for this invocation of the function object only. You could add static variables to your function, but those would be used for any invocation of the function. Second, the compiler can inline calls to the functor; it cannot do the same for … Read more
For lightweight randomnes (e.g. games), you could certainly consider default_random_engine. But if your code depends heavily on quality of randomness (e.g. simulation software), you shouldn’t use it, as it gives only minimalistic garantees: It is the library implemention’s selection of a generator that provides at least acceptable engine behavior for relatively casual, inexpert, and/or lightweight … Read more
It’s called exactly to avoid problems. A new object serving as result is initialized from the locally-defined object, then the locally defined object is destroyed. In case of deep-copy user-defined constructor it’s all the same. First storage is allocated for the object that will serve as result, then the copy constructor is called. It uses … Read more