Question

For an std::map<std::string, std::string> variables, I’d like to do this:

BOOST_CHECK_EQUAL(variables['a'], 'b'); 

The only problem is, in this context variables is const, so operator[] won’t work 🙁

Now, there are several workarounds to this; casting away the const, using variables.count('a') ? variables.find('a')->second : std::string() or even making a function wrapping that. None of these seem to me to be as nice as operator[]. What should I do? Is there a standard way of doing this (beautifully)?

Edit: Just to state the answer that none of you want to give: No, there is no convenient, beautiful, standard way of doing this in C++. I will have to implement a support function.

Answer 1

template <typename K, typename V> V get(std::map<K, V> const& map, K const& key) {     std::map<K, V>::const_iterator iter(map.find(key));     return iter != map.end() ? iter->second : V(); } 

Improved implementation based on comments:

template <typename T> typename T::mapped_type get(T const& map, typename T::key_type const& key) {     typename T::const_iterator iter(map.find(key));     return iter != map.end() ? iter->second : typename T::mapped_type(); }