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How can I handle data in C++ like in newer dynamic languages, for example the arrays in PHP are quite neat:
$arr = array( "somedata" => "Hello, yo, me being a simple string", "somearray" => array(6 => 5, 13 => 9, "a" => 42), "simple_data_again" => 198792, );
I am open to all suggestions.
If you know in advance what all kinds of values map is going to hold, then use boost::variant. Or else, use boost::any. With boost::any, you could later add entries with any type of value to the map.
Example code with boost::variant:
Creating a map:
typedef boost::variant<std::string, std::map<int, int>, int> MyVariantType; std::map<std::string, MyVariantType> hash;
Adding entries:
hash["somedata"] = "Hello, yo, me being a simple string"; std::map<int, int> temp; temp[6] = 5; temp[13] = 9; hash["somearray"] = temp; hash["simple_data_again"] = 198792;
Retrieving values:
std::string s = boost::get<std::string>(hash["somedata"]); int i = boost::get<int>(hash["simple_data_again"]);
As pointed out by @Matthieu M in the comments, the key-type of the map can be a boost::variant. This becomes possible because boost::variant provides a default operator< implementation providing the types within all provide it.
Example code with boost::any:
Creating a map:
std::map<std::string, boost::any> hash;
Adding entries:
hash["somedata"] = "Hello, yo, me being a simple string"; std::map<int, int> temp; temp[6] = 5; temp[13] = 9; hash["somearray"] = temp; hash["simple_data_again"] = 198792;
Retrieving values:
std::string s = boost::any_cast<std::string>(hash["somedata"]); int i = boost::any_cast<int>(hash["simple_data_again"]);
Thus, with help of boost::any the value-type in your map can be dynamic (sort of). The key-type is still static, and I don t know of any way how to make it dynamic.
A word of advice:
C++ is a statically typed language. The idioms like the one in your post which are used quite often in dynamic language don t fit well with the C++ language. Going against the grain of a language is a recipe for pain.
Therefore I d advise you not to try to emulate the idioms from your favorite dynamic languages in C++. Instead learn the C++ ways to do things, and try to apply them to your specific problem.
References:
License : cc by-sa 3.0
http://stackoverflow.com/questions/3690276/hierarchical-data-in-c
