proposal: fmt: add ReadLine() string

[earthboundkid]

Every few months, someone will post on Reddit that they're trying to make an intro to CS-style input prompt and they're confused why their code using fmt.Scan* doesn't work (inevitably because the input has a space and they're ignoring errors). I think that just for the use case of education, there should be something in fmt that does the thing that they want.

package fmt

// ReadLine attempts to read one line from os.Stdin. If it encounters an error, it returns "". 
// Advanced users may prefer to use a Scan function or bufio.Scanner.
func ReadLine() string

[seankhliao]

This doesn't belong in the fmt package, which is for "formatted I/O".

As you've observed, the correct place is bufio, and it already exists.

https://go.dev/doc/faq#x_in_std

[earthboundkid]

I disagree. fmt.Scan already exists and is an attractive nuisance to learners. I don't think my proposal has to be accepted by the Go team, but I also don't think it should be preemptively closed. My point isn't that this would be a useful function for professional programmers. My point is that today many new users are frustrated because their simple, intro-to-CS-style programs don't work.

Here are some typical posts:

• https://www.reddit.com/r/golang/comments/alvdhl/force_golang_to_scan_a_number_instead_of_a_single/
• https://www.reddit.com/r/golang/comments/atlehx/flushing_standard_input_before_scanf/
• https://www.reddit.com/r/golang/comments/2h5qnw/using_numerical_values_from_slices/
• https://www.reddit.com/r/golang/comments/wv1i2z/can_someone_tell_me_what_im_doing_wrong_im_trying/
• https://www.reddit.com/r/golang/comments/hkz1im/what_is_the_most_idiomatic_way_of_getting_input/
• https://www.reddit.com/r/golang/comments/8umvpt/unclear_on_scan/
• https://www.reddit.com/r/golang/comments/4hktbe/read_user_input_until_he_press_ctrlc/
• https://www.reddit.com/r/golang/comments/tq3wpc/scanln_and_scanf_jump_after_entering_string_value/
• https://www.reddit.com/r/golang/comments/qja60y/issues_with_fmtscanf_reading/
• https://www.reddit.com/r/golang/comments/kee82p/i_am_bit_confused_about_golangs_scanf/
• https://www.reddit.com/r/golang/comments/bkqos6/differences_between_scan_functions/
• https://www.reddit.com/r/golang/comments/whfi8p/question_about_fmtscan/
• https://www.reddit.com/r/golang/comments/p2tnio/in_golang_is_there_is_any_way_to_take_input/
• https://www.reddit.com/r/golang/comments/s85xxl/having_trouble_with_scanning_input_new_to_language/

You can find more by searching site:https://reddit.com/r/golang fmt.scan. There needs to be something very simple that novice can find without knowing anything about Go or IO. Obviously, they could and probably should be using bufio.Scanner already, but they aren't finding it today.

[seankhliao]

It looks like the forums are doing their job of educating users.

without knowing anything about Go or IO.

Is not a design goal for the standard library.

---

Indeed adding Scan* was a mistake too: #12275 (comment)

[earthboundkid]

New proposal: Deprecate Scan* functions.