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Quick Q: How can I make my constructor take a list of things, like map and vector? -- StackOverflow

By Blog Staff | Feb 21, 2014 01:28 PM | Tags: None

Quick A: By having your constructor take an initializer_list<> of the appropriate type.

Today on StackOverflow:

Constructor similar to std::map or std::vector in a class

I'm creating a class and I want to know how to create a constructor similar to the std::map or std::vector style.

std::map<std::string, std::string> map = {
    {"foo", "bar"},
    {"biz", "buz"},
    {"bez", "boz"}
};

The difference is that I don't want my class to ask for types that wants to accept, just like std::map does.

std::map<std::string, std::string>

I want my class to accept that style of arguments:

{
    {"foo", "bar"},
    {"biz", "buz"},
    {"bez", "boz"}
};

But with defined type. (std::string, Typer)

The 'Typer' is a class that I will insert as value on the std::map.

Thank you.

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Mikhail Semenov said on Mar 2, 2014 04:06 AM: 



#include <iostream>

#include <string>

#include <map>



typedef std::map<std::string, std::string> MyDataType;



class MyClass

{

 std::string name;

 MyDataType data;



public:

 MyClass(const std::string& name1, const MyDataType& data1) :name(name1), data(data1){}



 MyDataType getData() { return data; }

 std::string getName()  { return name; }



};





int main()

{

 MyClass x("special", 

    {

     { "foo", "bar" },

     { "biz", "buz" },

     { "bez", "boz" }

    }

 );



 MyDataType data = x.getData();

 for (auto& elem : data)

 {

  std::cout << elem.first << " " << elem.second << std::endl;

 }



 return 0;

}


This code works both in VS2013 and GCC 4.8.1