Question

I have to fill a std::vector with elements of type struct MHD_OptionItem.
This struct have this implementation:

struct MHD_OptionItem
{
    enum MHD_OPTION option;
    intptr_t value;
    void *ptr_value;
 };

I have tried this way:

 vector<struct MHD_OptionItem> iov;
 if(...)
     iov.push_back({ MHD_OPTION_NOTIFY_COMPLETED, requestCompleted, NULL });
 if(...)
     iov.push_back({ MHD_OPTION_CONNECTION_TIMEOUT, connectionTimeout });
 [....]

but the g++ compiler, as expected, says to me:

warning: extended initializer lists only available with -std=c++0x or -std=gnu++0x

I know that I can initialize a temporary struct and then pass it to the vector, but this method seems to me to be inefficient and not so elegant.

I can’t change the struct inserting a constructor because this is not my code but a library included.

There is an elegant way to do this without using c++0x syntax?

Answer 1

Assuming you cannot change the struct or you want to leave it a POD:

void f()
{
    struct {
        MHD_OptionItem operator ()(enum MHD_OPTION opt, intptr_t val, void *ptr = 0) {
            MHD_OptionItem x = {opt, val, ptr};
            return x;
        }
    } gen;

     vector<struct MHD_OptionItem> iov;
     if(...)
         iov.push_back(gen(MHD_OPTION_NOTIFY_COMPLETED, requestCompleted, NULL));
     if(...)
         iov.push_back(gen(MHD_OPTION_CONNECTION_TIMEOUT, connectionTimeout));
     [....]
}

Another solution:

    struct Gen : MHD_OptionItem {
        Gen(enum MHD_OPTION opt, intptr_t val, void *ptr = 0) {
            option = opt;
            value = val;
            ptr_value ptr;
        }
    };

     vector<struct MHD_OptionItem> iov;
     if(...)
         iov.push_back(Gen(MHD_OPTION_NOTIFY_COMPLETED, requestCompleted, NULL));
     if(...)
         iov.push_back(Gen(MHD_OPTION_CONNECTION_TIMEOUT, connectionTimeout));
     [....]