Macro ffi_convert::convert_to_c_string_result

macro_rules! convert_to_c_string_result {
    ($string:expr) => { ... };
}

A macro to convert a std::String to a C-compatible representation a raw pointer to libc::c_char wrapped in a Result enum. After calling this function, the caller is responsible for releasing the memory. The take_back_c_string! macro can be used for releasing the memory.