如何使用 swig 将 const 字符串参数从 perl 传递到 C++

Question

我是 Swig 的新手，我需要帮助来调试这个错误。

我的动机是使用 Swig、C++、Perl 创建一个耗时更少的日志系统。但是我在通过 swig 将 Perl 的字符串参数传递给 C++ 时出错。

我已将我的全部代码和错误放在下面。请帮我解决这个问题。以后谢谢了。

Logger.cpp

#include <stdexcept>

#include <string>
#include <ctime>
#include "Logger.h"

using namespace std;
Logger* Logger::pInstance = nullptr;




Logger& Logger::instance()
{
    lock_guard<mutex> guard(sMutex);
    printf("instance");
    if (pInstance == nullptr)
        pInstance = new Logger();
    return *pInstance;
}

void Logger::Cleanup()
{
    lock_guard<mutex> guard(Logger::sMutex);
    delete Logger::pInstance;
    Logger::pInstance = nullptr;
}


Logger::Logger()
{
    printf("Constructor\n");
    mOutputStream.open("log.out", ios_base::app);
    if (!mOutputStream.good()) {
        throw runtime_error("Unable to initialize the Logger!");
    } 

}
void Logger::log(const string& inMessage, const string& inLogLevel)
{
    lock_guard<mutex> guard(sMutex);
    logHelper(inMessage, inLogLevel);
}

void Logger::logHelper(const std::string& inMessage, const std::string& inLogLevel)
{
    mOutputStream << "[ " << current_time() << " ]" << inLogLevel << ": " << inMessage << endl;
}

string Logger::current_time()
{
    time_t rawtime;
  struct tm * timeinfo;
  char buffer[80];

  time (&rawtime);
  timeinfo = localtime(&rawtime);

  strftime(buffer,sizeof(buffer),"%d-%m-%Y %H:%M:%S",timeinfo);
  std::string str(buffer);
    return str;
}



Logger::~Logger(){
    printf("deconstructor\n");
    mOutputStream.close();
}

Logger.h

#ifndef LOGGER_H_
#define LOGGER_H_
#include <stdio.h>

#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <mutex>

class Logger
{
    public:
        Logger();
        ~Logger();
        Logger& instance();
        void log(const std::string& inMessage, 
        const std::string& inLogLevel);
    protected:
        static Logger* pInstance;
        std::ofstream mOutputStream;
        void Cleanup();
        void logHelper(const std::string& inMessage, 
        const std::string& inLogLevel);
    std::string current_time();
    private:


        std::mutex sMutex;
};
#endif

Logger.i

%module Logger 
%{
    #include "Logger.h"

%}

%include "Logger.h"

ch.pl

use strict;
use warnings;

use Cwd qw( abs_path );
use File::Basename qw( dirname );
use lib dirname(abs_path([=13=]));

use Logger;  

my $p=new Logger::Logger();
$p->instance();
$p->log("test message");

错误信息*

TypeError in method 'Logger_log', argument 2 of type 'std::string' at ch1.perl line 19.

Answer 1

您需要在接口文件中包含 std::string 的类型映射，以便 SWIG 知道如何处理该类型，请参阅 chapter 9.4 in the manual:

9.4.1 std::string The std_string.i library provides typemaps for converting C++ std::string objects to and from strings in the target scripting language.

%module Logger 
%include "std_string.i"
%{
    #include "Logger.h"
%} 
%include "Logger.h"

如果我这样使用运行 ch.pl：

use strict;
use warnings;
use lib '.';
use Logger;      
my $p = Logger::Logger->new();
$p->instance();
$p->log("test message", "DEBUG");

我得到输出：

Constructor
instanceConstructor
deconstructor

log.out文件的内容是：

[ 22-05-2020 17:35:12 ]DEBUG: test message

如何使用 swig 将 const 字符串参数从 perl 传递到 C++

How to pass const string parameter from perl to c++ using swig

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