Question

我得到例外：当我这样做时std :: bad_weak_ptr-＆gt; shared_from_this（）

template<typename TChar>
class painter_record_t
{
.......
private:
    std::shared_ptr<i_painter_t> _owner;
}

我想设置＆＃34;问题＆＃34;构造函数中的对象：

template<typename TChar>
class stream_record_t : public painter_record_t<TChar>
{
public:
    stream_record_t(std::shared_ptr<i_painter_t> owner) : painter_record_t(owner)
    {
    //...
    }
}

我有基类：

class i_painter_t
{
public:
    virtual std::unique_ptr<painter_record_t<char>> get_entry() = 0;
}

派生类，我希望将智能指针发送到基本抽象类，但得到异常：

class painter_t : public i_painter_t, public std::enable_shared_from_this<painter_t>
{
public:         

    std::unique_ptr<painter_record_t<char>> get_entry()
    {               
        return std::unique_ptr<painter_record_t<char>>(new stream_record_t<char>(static_cast< std::shared_ptr<i_painter_t> >(this->shared_from_this())));
    }
}

我也试过这个，但也有同样的问题：

class painter_t : public i_painter_t, public std::enable_shared_from_this<painter_t>
{
public:         

    std::unique_ptr<painter_record_t<char>> get_entry()
    {               
        return std::unique_ptr<painter_record_t<char>>(new stream_record_t<char>(this->shared_from_this()));
    }
}

Answer 1

要使enable_shared_from_this生效，您需要在调用#include "tools.h" static string vertexSource = getFile("D:/test.vsh"); static string fragmentSource = getFile("D:/test.fsh"); int main(int argc, char *argv[]) { //SDL/////////////////////////////////////////////// SDL_Init(SDL_INIT_EVERYTHING); SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4); SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 5); SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE); SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8); SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8); SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8); SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8); SDL_GL_SetAttribute(SDL_GL_ACCUM_RED_SIZE, 8); SDL_GL_SetAttribute(SDL_GL_ACCUM_GREEN_SIZE, 8); SDL_GL_SetAttribute(SDL_GL_ACCUM_BLUE_SIZE, 8); SDL_GL_SetAttribute(SDL_GL_ACCUM_ALPHA_SIZE, 8); SDL_Window *window = SDL_CreateWindow("Test", 50, 50, 1600, 900, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE); SDL_GLContext context = SDL_GL_CreateContext(window); //GLEW/////////////////////////////////////////////// glewExperimental = GL_TRUE; GLint result = glewInit(); if (result != GLEW_OK) { cout << glewGetErrorString(result) << "\n"; cout << "GLEW initialization failed.\n"; } //OpenGL/////////////////////////////////////////////// glEnable(GL_DEPTH); glDepthFunc(GL_LEQUAL); glEnable(GL_DEPTH_TEST); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glClearColor(1.0f, 1.0f, 0.0f, 1.0f); glClearDepth(1.0f); //Object/////////////////////////////////////////// //Vertex Array GLuint vao; glGenVertexArrays(1, &vao); glBindVertexArray(vao); //Vertex Buffer GLuint vbo; glGenBuffers(1, &vbo); GLfloat vertices[] = { -0.5f, 0.5f, 0.5f, 0.5f, 0.5f, -0.5f, -0.5f, -0.5f, }; glBindBuffer(GL_ARRAY_BUFFER, vbo); glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); //Element Buffer GLuint ebo; glGenBuffers(1, &ebo); GLuint elements[] = { 0, 1, 2, 2, 3, 0 }; glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW); //Shader GLuint shaderProgram = createShader(vertexSource, fragmentSource); glUseProgram(shaderProgram); GLint posAttrib = glGetAttribLocation(shaderProgram, "position"); glEnableVertexAttribArray(posAttrib); glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0); //Loop/////////////////////////////////////////////// float x = 0.0f; int step = 0; int steps = 4; SDL_Event eve; while (true) { //Test stuff x += 0.005f; GLfloat newVerts[] = { -0.5f + x, 0.5f, 0.5f + x, 0.5f, 0.5f + x, -0.5f, -0.5f + x, -0.5f, }; glBufferData(GL_ARRAY_BUFFER, sizeof(newVerts), newVerts, GL_STATIC_DRAW); //Normal stuff glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0); //Accumulation/////////////////////// if (step == 0) { glAccum(GL_LOAD, 1.0f / steps); } else { glAccum(GL_ACCUM, 1.0f / steps); } step++; if (step < steps) { continue; } step = 0; glAccum(GL_RETURN, 1.0f); //Accumulation/////////////////////// SDL_GL_SwapWindow(window); SDL_PollEvent(&eve); } }之前将指针存储在this中的std::shared_ptr。

请注意，在对象t上调用shared_from_this之前，必须有一个拥有t的std :: shared_ptr。

您可能希望将shared_from_this()构造函数设为私有，并公开工厂方法，以确保创建的每个painter_t都由painter_t管理：

shared_ptr

例外：bad_weak_ptr而shared_from_this

1 个答案: