One Handler, Three Messages

1#include <iostream>
2#include <stdexcept>
3#include <string>
4 
5class ParseError : public std::runtime_error {
6public:
7    explicit ParseError(const std::string& m) : std::runtime_error(m) {}
8};
9 
10class MissingField : public ParseError {
11public:
12    explicit MissingField(const std::string& field) : ParseError("missing field " + field) {}
13};
14 
15class BadNumber : public ParseError {
16public:
17    explicit BadNumber(const std::string& text) : ParseError("bad number " + text) {}
18};
19 
20void parse(int line) {
21    if (line == 1) {
22        throw MissingField("name");
23    }
24    if (line == 2) {
25        throw BadNumber("x7");
26    }
27    if (line == 3) {
28        throw ParseError("line too long");
29    }
30    std::cout << "line " << line << " parsed\n";
31}
32 
33int main() {
34    for (int line = 0; line <= 3; line++) {
35        try {
36            parse(line);
37        } catch (const ParseError& e) {
38            std::cout << "stopped on line " << line << ": " << e.what() << "\n";
39        }
40    }
41    return 0;
42}