Error Class

The Error class is used for creating custom error messages with line number and file name information in C++ programs.

Preprocessor Definition

The preprocessor definition Exception(message) is defined as Error(message, __LINE__, __FILE__), which creates an instance of the Error class with the provided message, line number, and file name (the line number and file name are from where the Exception(message) was called).

#define Exception(message) Error(message, __LINE__, __FILE__)

Class Definition

The Error class is defined with two constructors and a public member function.

Constructors

The first constructor takes in a const std::string& parameter for the message and initializes the private message_ member variable with the provided message.

Error::Error(const std::string &message) : message_(message) {}

The second constructor takes in a const std::string& parameter for the message, an int parameter for the line number, and a const char* parameter for the file name. It creates the message by concatenating the provided message, the line number, and the file name, and then initializes the private message_ member variable with the concatenated string.

Error::Error(const std::string &message, int line, const char *file)
{
    message_ = message + "\nexception at line " + std::to_string(line) + ", " + file;
}

Public Member Function

The message() function is a public member function that returns the private message_ member variable as a string.

std::string Error::message() const
{
    return message_;
}

Usage

The following code snippet creates an instance of the Error class and throws an exception:

#include "assertion.hpp"

int main()
{
    try
    {
        throw(Exception("An error occurred"));
    }
    catch (const Error& e)
    {
        std::cerr << e.message() << std::endl;
    }
    return 0;
}

The try block throws an exception using the Exception preprocessor definition. The catch block catches the exception as a const Error& reference and calls the message() function to retrieve the error message.

The terminal should display the following:

An error occurred
exception at line 7, src/Debug.cpp