Core utilities
Core utility library by Ross Smith
#include "rs-core/format.hpp"
namespace RS;
template <typename T> struct std::formatter<T>;
A formatter is automatically generated for any user defined type for which a
function named rs_core_format() exists. This can be a member function or a
free function in the same namespace as the UDT. It can optionally take a
formatting flags argument (a string or string view), a size argument
(an integer), or both. The return type can be a string or string view.
Any of the following signatures will be recognized (in this order of preference):
[string or view] T::rs_core_format(std::string_view flags,
std::size_t size) const;[string or view] rs_core_format(const T& t, std::string_view flags,
std::size_t size);[string or view] T::rs_core_format(std::string_view flags) const;[string or view] rs_core_format(const T& t, std::string_view flags);[string or view] T::rs_core_format(std::size_t size) const;[string or view] rs_core_format(const T& t, std::size_t size);[string or view] T::rs_core_format() const;[string or view] rs_core_format(const T& t);If the formatting function takes a flags argument, the generated formatter will accept any character except null, digits, or braces as part of the flags argument; interpreting them is up to the user defined formatting function. The flags in a formatting call are limited to a maximum of 16 bytes.
Formatting to output string types other than plain std::string is not
supported.
Example:
class MyClass {
std::string str(std::string_view flags) const;
};
std::string rs_core_format(const MyClass& x, std::string_view flags) {
return x.str(flags);
}
MyClass x;
std::println("{}", x); // OK, generates default format
std::println("{:abc}", x); // OK, calls x.str("abc")
std::println("{:42}", x); // Compile error, no int argument allowed