user690421 user690421 - 1 year ago 72
C++ Question

C++ alternatives to Java static blocks

I am writing a date class where I want a static map to map "Jan" to 1 and so on. I am wondering how I can initialize that static map. This is what I am currently doing, but I just feel that the extra if statement is inelegant compared with static block in Java. I understand the compilation of C++ program is much more complicated, but I still wonder whether a better solution exists.

class date {
static map<string, int> month_map;
int month;
int year;
class input_format_exception {};
date(const string&);
bool operator< (const date&) const;
string tostring() const;

map<string, int> date::month_map = map<string,int>();

date::date(const string& s) {
static bool first = true;
if (first) {
first = false;
month_map["Jan"] = 1;
month_map["Feb"] = 2;
month_map["Mar"] = 3;
month_map["Apr"] = 4;
month_map["May"] = 5;
month_map["Jun"] = 6;
month_map["Jul"] = 7;
month_map["Aug"] = 8;
month_map["Sep"] = 9;
month_map["Oct"] = 10;
month_map["Nov"] = 11;
month_map["Dec"] = 12;
// the rest code.

// the rest code.

Answer Source

For non-c++11 systems: how about using a helper function and make month_map a static const member of date as it looks like you never wan't to change the association of the month's name with it's number, do you? This way month_map is initialized in your cpp-File and not in your constructor where it just messes things up. (Maybe you'll have several constructors in the future then you'll have to write a lot of boilerplate code)

const std::map<string, int> createMonthMap()
   std::map<string, int> result;

   // do init stuff

   return result;

const std::map<string, int> data::month_map(createMonthMap());
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