从Windows窗体类调用PThread到Windows窗体类内的函数

Question

我在Visual Studio 2008 Professional的Windows窗体上使用pthread，但在示例源代码中显示的行中出现错误。可能是因为它是C++/CLI，因为它通常在常规类中工作。问题出在这一行：

（（TestGUI*）上下文）->TestxFunc（）；

在函数StaticCallFunc 中

public ref class TestGUI : public System::Windows::Forms::Form {
        /...
    public:
void TestxFunc(std::string test, std::string test2){
        this->btn_next->Enabled = false;
        cout << "HI, Test: " << test << "," << " Test 2: " << test2 << endl;
 }
static void *StaticCallFunc(void *context){
    std::string test = "foo";
    std::string test2 = "bar";
    printf("nStarting Thread");
    ((TestGUI*)context)->TestxFunc(); //Line with the error down.
    return 0;
} 
System::Void tester_Click(System::Object^  sender, System::EventArgs^  e) {
      pthread_t t;
      pthread_create(&t, NULL, &TestGUI::StaticCallFunc, this);
}
//...

错误C3699:"：无法对类型"Test:：TestxFunc"1>使用此间接寻址编译器将"*"替换为"^"以继续分析

错误C2227："->TestxFunc"的左侧必须指向类/结构/联合/通用类型

我该怎么办才能解决这个问题？这个调用通常适用于常规类，但在Windows窗体中它实际上不适用于

Answer 1

由于TestGUI是CLI/C++类，您应该使用^而不是*来取消引用其指针，但这不是唯一的问题。您似乎想要在pthread中执行CLI/C++类成员方法。要使其工作，您可以尝试以下方法：

*从TestGUI类中删除StaticCallFunc，并使其成为全局方法
*要将TestGUI指针传递给非托管函数，可以使用gcroot。因此，定义一个容器类，例如PtrContainer，它将gcroot作为成员

//dont forget forward declerations
void *StaticCallFunc(void *context); //forward decleration
ref class TestGUI; //forward decleration
//Define a simple argument class to pass pthread_create
struct PtrContainer{
     gcroot<TestGUI^> guiPtr; //you need to include vcclr.h for this
};

当您绑定到pthread_create时，您可以按如下方式使用PtrContainer：

System::Void tester_Click(System::Object^  sender, System::EventArgs^  e) {
    //init. container pointer,
    //we use dynamically allocated object because the thread may use it after this method return
    PtrContainer* ptr = new PtrContainer;
    ptr->guiPtr = this;
    pthread_t t;
    pthread_create(&t, NULL, StaticCallFunc, ptr );
}

您应该删除驱动程序方法（StaticCallFunc）中的容器指针：

void *StaticCallFunc(void *context){
    std::string test = "foo";
    std::string test2 = "bar";
    printf("nStarting Thread");
    PtrContainer* ptr = reinterpret_cast<PtrContainer*>(context);
    ptr->guiPtr->TestxFunc(test, test2);
    //dont forget to delete the container ptr.
    delete ptr;
    return 0;
}

再来一个音符；以多线程方式访问.NET gui组件时，必须小心以线程安全的方式调用控件。

编辑：我添加了以下完整的源代码，它在Visual Studio 11、Windows7下编译和工作

//sample.cpp
#include <iostream>
#include <string>
#include <vcclr.h>
#include <sstream>
using namespace std;
using namespace System;
using namespace System::Windows::Forms;
#include "pthread.h"
#include <stdio.h>
#define PTW32_THREAD_NULL_ID {NULL,0}
#define int64_t _int64
void *StaticCallFunc(void *context); //forward decleration
ref class TestGUI; //forward decleration
//Define a simple argument class to pass pthread_create
struct PtrContainer{
    gcroot<TestGUI^> guiPtr; //you need to include vcclr.h for this
};
ref class TestGUI : public System::Windows::Forms::Form  
{
public:
    TestGUI(void) {
        this->Click += gcnew System::EventHandler(this, &TestGUI::tester_Click );
    }
    void TestxFunc(std::string test, std::string test2){
            cout << "HI, Test: " << test << "," << " Test 2: " << test2 << endl;
    }
    System::Void tester_Click(System::Object^  sender, System::EventArgs^  e) {
        //init. container pointer,
        //we use dynamically allocated object because the thread may use it after this method return
        PtrContainer* ptr = new PtrContainer;
        ptr->guiPtr = this;
        pthread_t t;
        pthread_create(&t, NULL, StaticCallFunc, ptr );
    }
};
void *StaticCallFunc(void *context){
    std::string test = "foo";
    std::string test2 = "bar";
    printf("nStarting Thread");
    PtrContainer* ptr = reinterpret_cast<PtrContainer*>(context);
    ptr->guiPtr->TestxFunc(test, test2);
    //dont forget to delete the container ptr.
    delete ptr;
    return 0;
}
int main()
{
    TestGUI^ testGui = gcnew TestGUI();
    testGui->ShowDialog();
    return 0;
}

编译者：

/analyze- /clr /Od /nologo /MDd /Gm- /Fa".Debug" /I".." /Oy- /FU"C:Program Files (x86)Reference AssembliesMicrosoftFramework.NETFrameworkv4.0mscorlib.dll" /FU"C:Program Files (x86)Reference AssembliesMicrosoftFramework.NETFrameworkv4.0System.dll" /FU"C:Program Files (x86)Reference AssembliesMicrosoftFramework.NETFrameworkv4.0System.Windows.Forms.dll" /Zc:forScope /Fo".Debug" /Gy- /Fp".DebugDebug.pch" /D "WIN32" /D "_DEBUG" /D "_CONSOLE" /D "CLEANUP_C" /D "_VC80_UPGRADE=0x0600" /D "_MBCS" /WX /errorReport:queue /GS /Fd".Debug" /fp:precise /FR".Debug" /W3 /Z7 /Zc:wchar_t /EHa