On Tuesday, 16 September 2014 at 15:30:49 UTC, Andrei
Alexandrescu wrote:
http://www.slideshare.net/yandex/rust-c
C++ code:
std::string get_url() {
return "http://yandex.ru";;
}
string_view get_scheme_from_url(string_view url) {
unsigned colon = url.find(':');
return url.substr(0, colon);
}
int main() {
auto scheme = get_scheme_from_url(get_url());
std::cout << scheme << "\n";
return 0;
}
string_view has an implicit constructor from const string& (see
"basic_string_view(const basic_string<charT, traits,
Allocator>& str) noexcept;" in
https://isocpp.org/files/papers/N3762.html). The function
get_url() returns an rvalue, which in turn gets bound to a
Forgive me my ignorance but get_url() returns a std::string (on
the stack), so its address can be token.
And iirc the explainer Scott Meyers explained once "iff you can
take its address its not a rvalue its a lvalue". So isn't the
get_scheme_from_url() not simply holding a const ref to
temporary? (which most compiler warn about)
...Or am I missing the point?
reference to const and implicitly passed to string_view's
constructor. The obtained view refers to a dead string.
Andrei
