I implemented a generic event emitter class which allows code to register callbacks, and emit events with arguments. I used Boost.Any type erasure to store the callbacks so they can have arbitrary parameter signatures. It all works, but for some reason, lambdas being passed in must first be turned into std::function objects. Why doesn't the compiler infer that the lambda is the function t
我实现了一个通用事件发射器类，它允许代码注册回调，并用参数发出事件。 我使用Boost.Any类型的擦除来存储回调，以便他们可以有任意的参数签名。 这一切都有效，但由于某种原因，传入的lambda必须先转换为std::function对象。 为什么编译器不推断lambda是函数类型？ 是因为我使用可变模板的方式吗？ 我使用Clang（版本字符串： Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) ）。 码： #include &l
While there's a lot of stuff floating out there about getting the return type of any templated callback function/method (including lambdas of course), I'm having an extremely hard time finding information about resolving the full call signature of a lambda function. At least in gcc 4.7 it seems to be an edge case where the normal tricks (see below) don't work. Here's what I'
虽然有很多关于获取任何模板化回调函数/方法（包括lambda当然）的返回类型的东西，但我很难找到有关解析lambda函数的完整调用签名的信息。 至少在gcc 4.7中，这似乎是一个正常窍门（见下文）不起作用的边缘情况。 这是我正在尝试做的，迄今为止（当然是精简版）...... template<typename Sig> struct invokable_type { }; template<typename R, typename...As> struct invokable_type<R(As...)> { stati
I'm trying to find a method to iterate over an a pack variadic template argument list. Now as with all iterations, you need some sort of method of knowing how many arguments are in the packed list, and more importantly how to individually get data from a packed argument list. The general idea is to iterate over the list, store all data of type int into a vector, store all data of type char
我试图找到一个方法来迭代一个pack variadic模板参数列表。 现在和所有迭代一样，您需要某种方法来了解打包列表中有多少个参数，更重要的是，如何从一个打包参数列表中单独获取数据。 总的想法是迭代列表，将int类型的所有数据存储到一个向量中，将所有类型为char *的数据存储到向量中，并将所有类型为float的数据存储到向量中。 在这个过程中，还需要一个单独的向量来存储参数进入顺序的个别字符。例如，当您push_back（a_f
The following code produces undefined reference error on c++ (Debian 4.7.2-5) 4.7.2 : #include <signal.h> class Lol { public: void foo() { struct sigaction sa; sa.sa_flags = 0; sigemptyset(&sa.sa_mask); sa.sa_handler = [](int) { }; sigaction(SIGTERM, &sa, 0); } }; int main() { Lol l; l.foo(); } lev@debi7:~$ c++ -std
以下代码在c++ (Debian 4.7.2-5) 4.7.2上产生undefined reference错误： #include <signal.h> class Lol { public: void foo() { struct sigaction sa; sa.sa_flags = 0; sigemptyset(&sa.sa_mask); sa.sa_handler = [](int) { }; sigaction(SIGTERM, &sa, 0); } }; int main() { Lol l; l.foo(); } lev@debi7:~$ c++ -std=c++11 -o lol lol.
I have a static class method that needs access to a pointer MyTypePointer that therefore has to be declared static. Since it is a template class I have to put the methods inside the header file but I can't define MyTypePointer in the header. So I get the "undefined Reference" error since MyTypePointer is not declared. How can I make this work / declare MyTypePointer. myclass.h
我有一个静态类方法，需要访问指针MyTypePointer，因此必须声明为静态。 由于它是一个模板类，我必须将这些方法放在头文件中，但是我不能在头中定义MyTypePointer。 所以我得到“未定义的引用”错误，因为MyTypePointer没有声明。 我如何使这个工作/声明MyTypePointer。 myclass.h template <typename A, typename B> class PathfindingClass { typedef std::vector<GenericEdgeClass<A, B>*> MyType;
I realize something similar has been asked before (glfw3 compiling undefined references), but I still can't get it to work unfortunately. Any help is welcome! Below is the compiler output when running make: g++ -std=c++11 -Wall -Wextra -Werror -pedantic-errors -I/usr/local/include -c -o Main.o Main.cpp g++ -std=c++11 -Wall -Wextra -Werror -pedantic-errors -I/usr/local/include -L/usr/lo
我意识到之前曾经有人问过类似的问题（glfw3编译未定义的引用），但我仍然不能很好地工作。 欢迎任何帮助！ 下面是运行make时的编译器输出： g ++ -std = c ++ 11 -Wall -Wextra -Werror -pedantic-errors -I / usr / local / include -c -o Main.o Main.cpp g ++ -std = c ++ 11 -Wall -Wextra -Werror -pedantic-errors -I / usr / local / include -L / usr / local / lib -lglfw3 -lGL Main.o -o modernogl Main.o
Can't seem to get the errors to go away. Errors are below. I have looked on google and still can't figure it out. It is not like I am new to Cpp, but have not fooled with it in a while. Weird thing is it worked with G++ in Windows... Errors: [ze@fed0r! ---**__*]$ g++ main.cpp /tmp/ccJL2ZHE.o: In function `main': main.cpp:(.text+0x11): undefined reference to `Help::Help()
似乎无法让错误消失。 错误如下。 我看过谷歌，仍然无法弄清楚。 这不像我是Cpp的新手，但一段时间没有被愚弄。 奇怪的是它在Windows中使用G ++ ... 错误： [泽@ fed0r！ --- ** __ *] $ g ++ main.cpp /tmp/ccJL2ZHE.o：在函数`main'中： main.cpp :( .text + 0x11）：对`Help :: Help（）'的未定义引用 main.cpp :( .text + 0x1d）：对`Help :: sayName（）'的未定义引用 main.cpp :( .text + 0
I can't understand, why if we define static variable of usual (non-template) class in header, we have linker error, but in case of templates all works fine and moreover we will have single instance of static variable among all translation units: It's template header (template.h): // template.h template<typename T> class Templ { public: static int templStatic; }; template<ty
我无法理解，为什么如果我们在头文件中定义了常用（非模板）类的静态变量，我们有链接器错误，但是如果模板全部正常工作，并且我们将在所有翻译单元之间具有单个静态变量实例： 它是模板头（template.h）： // template.h template<typename T> class Templ { public: static int templStatic; }; template<typename T> Templ<T>::templStatic = 0; 它是使用模板的第一个单元（unit1.cpp） // unit1.cp
This question already has an answer here: What is the difference between a 'closure' and a 'lambda'? 10 answers Quoting the Go language specification: Function literals A function literal represents an anonymous function. FunctionLit = "func" Function . func(a, b int, z float64) bool { return a*b < int(z) } A function literal can be assigned to a variable or invoked
这个问题在这里已经有了答案： '封'和'lambda'有什么区别？ 10个答案 引用Go语言规范： 函数文字 函数文字表示一个匿名函数。 FunctionLit = "func" Function . func(a, b int, z float64) bool { return a*b < int(z) } 函数文字可以分配给变量或直接调用。 f := func(x, y int) int { return x + y } func(ch chan int) { ch <- ACK }(replyChan) 函数文字是闭包：它们可能引用周围函数中
I have a C++ framework I would like to use in Objective-C++. I'm working in XCode4 and targeting an iPad deployment. So given this (pseudocode) C++ header: class A { public: virtual int doSomething(int i) = 0; private: int _i; } For this specific instance, I need to have doSomething dispatch something via Grand Central Dispatch. I'm having trouble finding solutions to imple
我有一个C ++框架，我想在Objective-C ++中使用。 我正在使用XCode4并定位iPad部署。 所以给了这个（伪代码）C ++头文件： class A { public: virtual int doSomething(int i) = 0; private: int _i; } 对于这个特定的情况下，我需要有doSomething通过大中央调度派遣的东西。 我很难找到在Objective-C ++中实现C ++头文件的解决方案。 是否有可能这样做？ 如果是这样，有人可以提供一个很好的例子吗？ 谢谢！