C++ constructor: Initialize local variable before initializer list

With C++11 you could solve this with delegating constructors:

class ConfigAbstraction
{
public:
    ConfigAbstraction(std::istream& input);

private:
    ConfigAbstraction(const MySillyParserDontWorry& parser);

    int m_a;
    int m_b;
    int m_c;
};

ConfigAbstraction::ConfigAbstraction(const MySillyParserDontWorry& parser)
    : m_a{parser.intByName("a")}
    , m_b{parser.intByName("b")}
    , m_c{parser.intByName("c")}
{
}

ConfigAbstraction::ConfigAbstraction(std::istream& input)
    : ConfigAbstraction{MySillyParserDontWorry{input}}
{
}