Preface
The first part lang: Summarize the syntax of 9 programming languages to design the exception handling information in Suatin-lang . In fact, the exception information format of many languages is very similar. This article uses C++ custom exception classes , and uses C++ exception handling to handle the exceptions of the upper language Suatin-lang.
Enumeration information
Enumerate all the error types, click this when printing exception information.
enum SuaError {
NoDefinedError, //未定义
ZeroError, //不该出现零的地方出现了零
IOError, //输入输出或文件操作出现问题
ValueError, //对已经有类型的变量传递了其他的类型
OtherError //不属于上面错误的其他类型错误
};
Display exception information
//自定义异常类省略（仮）
/*
异常信息有：
dir 文件路径
lineNumber 行数
area 代码作用域
lineContent 该行内容
description 异常描述
*/
template<int error>
void SelectException(std::string dir,int lineNumber,std::string area,std::string lineContent,std::string description) {
std::string errorString = "Traceback at : File \"" + dir + "\",line " + std::to_string(lineNumber)+" in <"+area+">\n\t"+lineContent+"\n";
switch (error) {
case NoDefinedError:
errorString += "NoDefinedError : " + description + "\n";
break;
case ZeroError:
errorString += "ZeroError : " + description + "\n";
break;
case IOError:
errorString += "IOError : " + description + "\n";
break;
case ValueError:
errorString += "ValueError : " + description + "\n";
break;
case OtherError:
default:
errorString += "OtherError : " + description + "\n";
break;
}
//std::cout << errorString << std::endl;
throw SuaExcept(errorString);
}
void main(void) {
try {
int a = 0;
if (a == 0) {
SelectException<NoDefinedError>("E:/Can/Suatin/test.sua",
120,"module","sum = sum + i", "i is not defined");
}
}
catch (SuaExcept& e) {
std::cout << e.what()<<std::endl;
}
system("pause");
}
Error demonstration of custom exception class
Because I want to pass an exception message to be printed in the past, so I write
class SuaExcept : public std::exception
{
const char* error;
public:
SuaExcept(std::string error) {
this->error=error.c_str();
}
virtual const char* what()const throw() {
return this->error;
}
};
But it prints garbled characters! Debugging found that the error was indeed passed, but the custom exception class was called again when the exception was caught, and the e address obtained did not change, indicating that it was caught! But no content? ? ? ?
- I don't know what the problem is.
Correct custom exception class
class SuaExcept : public std::exception
{
public:
SuaExcept(std::string error) : exception(error.c_str()){
}
};
Output is
Traceback at : File "E:/Can/Suatin/test.sua",line 120 in <module>
sum = sum + i
NoDefinedError : i is not defined