Will the initialization list always be processed before the constructor code?

Will the initialization list always be processed before the constructor code?

In other words, will the following code always print <unknown>, and the constructed class will have "known" as value for source_ (if the global variable something is true)?

class Foo {
  std::string source_;
public:
  Foo() : source_("<unknown>") {
    std::cout << source_ << std::endl;
    if(something){
      source_ = "known";
    }
  }
};