Problem

The current ifstream/ofstream API allows illogical mode combinations:

  std::ifstream f("data.txt", std::ios::out); // Compiles, but doesn't work

Modes are bitmasks, error-prone, and not checked at compile time.

The current std::ios::openmode is an unscoped bitmask with limited type safety and poor readability.

Proposal

This proposal introduces a strongly typed alternative using enum class Mode, enabling clearer semantics, safer combinations, and future extensibility.

auto f = open_file<Mode::read>("data.txt");

auto g = open_file<write | Mode ::binary>("log.bin");

Mode

The mode is now explicit and scoped, reducing ambiguity and improving code clarity. Bitwise combinations are supported via overloaded operators, and modes can be introspected or validated at compile-time.

The template parameter Mode uses an enum class for clarity and safety. :

enum class Mode : std::uint8_t {

    read    = 0x01,

    write   = 0x02,

    binary  = 0x04,

    append  = 0x08

};

 

Benefits