Feature request: `fmt::to_string`

[netheril96]

Basically the same as std::to_string. It should not be hard to implement as it is functionally equivalent to fmt::format("{}", XXX). Reasons that I would like to use fmt::to_string in lieu of std::to_string:

• std::to_string is not available on C++03.
• std::to_string is horrendously slow on some implementations. Last time I checked, MSVC internally creates a stringstream for every std::to_string call.

[vitaut]

Good idea. It can even be implemented in a more efficient way than fmt::format("{}", XXX), something like:

template <typename T>
std::string to_string(const T &value) {
  fmt::MemoryWriter w;
  w << value;
  return w.str();
}

Or, even better, writing directly to std::string with a writer described in #292.

[vitaut]

Done in b6c0cf9. fmt::to_string is defined in a separate header, fmt/string.h.

[vitaut]

It's documented here: http://fmtlib.net/dev/api.html#_CPPv2N3fmt9to_stringERK1T

[alabuzhev]

Could you please add fmt::to_wstring as well?

[vitaut]

@alabuzhev Would you be willing to submit a pull request along the lines of b6c0cf9? =)