Own exception in C++ can not be thrown

Question

I'm trying to get a custom exception in C++ working (Linux, g++). Dictionary.hpp :

#ifndef HEADER_DICTIONARY_H
#define HEADER_DICTIONARY_H

#include <map>
#include <string>
#include <stdexcept>

using namespace std;

[...]

class EDictionaryNoLabel : public runtime_error
{
public:
          explicit EDictionaryNoLabel(const string& __arg);
          virtual ~EDictionaryNoLabel() _GLIBCXX_USE_NOEXCEPT;
};

#endif

And in Dictionary.cpp I throw the exception (here is where the compilation fails):

#include <map>
#include <string>
#include "Dictionary.hpp"

using namespace std;

//  map<string, string> dictMap;
Dictionary::Dictionary() {
}

void Dictionary::update(string label, string value) {
        dictMap[label]=value;
}

string Dictionary::read(string label){
        if (0==dictMap.count(label)) {
                throw( EDictionaryNoLabel("label not found") );
        }
        return dictMap[label];
}

void Dictionary::refresh() {
        dictMap.clear();
}

But I can not compile it:

utils/Dictionary.o: In function `Dictionary::read(std::string)':
Dictionary.cpp:(.text+0xbf): undefined reference to `EDictionaryNoLabel::EDictionaryNoLabel(std::string const&)'
Dictionary.cpp:(.text+0xdc): undefined reference to `EDictionaryNoLabel::~EDictionaryNoLabel()'
Dictionary.cpp:(.text+0xe1): undefined reference to `typeinfo for EDictionaryNoLabel'
/tmp/ccXT7dWk.o:(.gcc_except_table+0x68): undefined reference to `typeinfo for EDictionaryNoLabel'
collect2: error: ld returned 1 exit status
make: *** [Test] Error 1

I write my exception exactly as the standard overflow_error (also inheriting from runtime_error ).

Answer 1

A very easy and effective way to derive your own exceptions is:

struct EDictionaryNoLabel : std::runtime_error
{
    using std::runtime_error::runtime_error;
};

That's it.

This gives you all the standard constructors and type-safety. Plus you can add further methods if you need them.

anticipating:

What does using std::runtime_error::runtime_error; do?

copies the names of the base class's constructors into this class's namespace. It gives you all the base class's constructors with no extra code.