matlab - 如何将 Matlab 类编译成 C 库？

Question

这个问题的来源是这里How to use "global static" variable in matlab function called in c .

我试图将“全局变量”封装到一个对象中。但是我不知道如何使用 MATLAB Compiler (mcc) 将 matlab 类导出到 C++

为此我只是尝试了标准命令

Matlab 命令

mcc -W cpplib:Vowel4 -T link:lib Vowel4.m

Matlab 脚本

classdef Vowel4

  properties
    x
    y
  end

  methods
    Vowel4
    A
    B
  end

end

生成的lib实际上是独立的函数而不是c++类。

如何将 Matlab 中的类编译成 C++ 类？

我一直在寻找答案，但没有找到。

显然matlab命令不适合这种场景。但是我找不到任何关于将 Matlab 类构建为 C++ 类的信息。

==========================编辑==================== ====

实际的cpp代码如下:@Alan

mclInitializeApplication(NULL, 0);
loadDataInitialize();
soundByCoefInitialize();
loadData(); 

mwArray F(4, 1, mxDOUBLE_CLASS);
float test[4];

for ( ;; ){
    const Frame frame = controller.frame();
    const FingerList fingers = frame.fingers();
    if ( !fingers.empty() ){
        for ( int i = 0; i < 4; i ++ ){
            double v = fingers.count() > i ? (fingers[i].tipPosition().y / 50) - 2 : 0;
            F(i+1,1) = v;
            test[i] = v;
            cout << v << ' ';
        }
        cout << endl;
        soundByCoef(F);
    }
}

这里的 matlabA() 对应于加载数据的 loadData()，而 soundByCoef(F) 对应于 matlabB()，后者在主循环中完成工作。

Answer 1

正如艾伦所说，I was只建议使用句柄类作为全局变量的容器(这样的对象将通过引用传递)。创建的对象不打算由您的 C++ 代码直接操作(它将存储在通用 mxArray/mwArray C/C++ 结构中)。

As far作为I know ，在使用 MATLAB 编译器构建共享库时，您不能直接将 classdef 样式的 MATLAB 类编译为正确的 C++ 类。它只支持构建常规函数。您可以为 MATLAB 类成员方法创建功能接口(interface)，但那是另一回事...

也许一个完整的例子可以帮助说明我的想法。首先让我们在 MATLAB 端定义代码:

全局数据.m

这是用于存储全局变量的句柄类。

classdef GlobalData < handle
    %GLOBALDATA  Handle class to encapsulate all global state data.
    %
    % Note that we are not taking advantage of any object-oriented programming
    % concept in this code. This class acts only as a container for publicly
    % accessible properties for the otherwise global variables.
    %
    % To manipulate these globals from C++, you should create the class API
    % as normal MATLAB functions to be compiled and exposed as regular C
    % functions by the shared library.
    % For example: create(), get(), set(), ...
    %
    % The reason we use a handle-class instead of regular variables/structs
    % is that handle-class objects get passed by reference.
    %

    properties
        val
    end
end

create_globals.m

作为上述类的构造函数的包装函数

function globals = create_globals()
    %CREATE_GLOBALS  Instantiate and return global state

    globals = GlobalData();
    globals.val = 2;
end

fcn_add.m, fcn_times.m

要公开为 C++ 函数的 MATLAB 函数

function out = fcn_add(globals, in)
    % receives array, and return "input+val" (where val is global)

    out = in + globals.val;
end

function out = fcn_times(globals, in)
    % receives array, and return "input*val" (where val is global)

    out = in .* globals.val;
end

将上述文件存储在当前目录中，让我们使用 MATLAB 编译器构建 C++ 共享库:

>> mkdir out
>> mcc -W cpplib:libfoo -T link:lib -N -v -d ./out create_globals.m fcn_add.m fcn_times.m

除其他外，您应该期望生成以下文件(我在 Windows 机器上):

./out/libfoo.h
./out/libfoo.dll
./out/libfoo.lib

接下来，我们可以创建一个示例 C++ 程序来测试该库:

main.cpp

// Sample program that calls a C++ shared library created using
// the MATLAB Compiler.

#include <iostream>
using namespace std;

// include library header generated by MATLAB Compiler
#include "libfoo.h"

int run_main(int argc, char **argv)
{
    // initialize MCR
    if (!mclInitializeApplication(NULL,0)) {
        cerr << "Failed to init MCR" << endl;
        return -1;
    }

    // initialize our library
    if( !libfooInitialize() ) {
        cerr << "Failed to init library" << endl;
        return -1;
    }

    try {
        // create global variables
        mwArray globals;
        create_globals(1, globals);

        // create input array
        double data[] = {1,2,3,4,5,6,7,8,9};
        mwArray in(3, 3, mxDOUBLE_CLASS, mxREAL);
        in.SetData(data, 9);

        // create output array, and call library functions
        mwArray out;
        fcn_add(1, out, globals, in);
        cout << "Added matrix:\n" << out << endl;
        fcn_times(1, out, globals, in);
        cout << "Multiplied matrix:\n" << out << endl;
    } catch (const mwException& e) {
        cerr << e.what() << endl;
        return -1;
    } catch (...) {
        cerr << "Unexpected error thrown" << endl;
        return -1;
    }

    // destruct our library
    libfooTerminate();

    // shutdown MCR
    mclTerminateApplication();

    return 0;
}

int main()
{
    mclmcrInitialize();
    return mclRunMain((mclMainFcnType)run_main, 0, NULL);
}

让我们构建独立程序:

>> mbuild -I./out main.cpp ./out/libfoo.lib -outdir ./out

最后运行可执行文件:

>> cd out
>> !main
Added matrix: 
     3     6     9 
     4     7    10 
     5     8    11 
Multiplied matrix: 
     2     8    14 
     4    10    16 
     6    12    18 

HTH