proposal: log: add flag to use hyphen instead of slash as separator

[TwiN]

What version of Go are you using (go version)?

$ go version
1.17.1

Does this issue reproduce with the latest release?

Yes

What did you do?

package main

import "log"

func main() {
    log.Println("Hello, world.")
}

What did you expect to see?

2021-12-15 19:12:34 Hello, world.

To clarify, I'd be fine with this being configurable via a flag (i.e. log.SetFlags(log.LstdFlags | log.LdateHyphenSeparator) where log.LdateHyphenSeparator would be a new flag) for the sake of backward compatibility.

What did you see instead?

2021/12/15 19:12:34 Hello, world.

Explanation

This has been one of my biggest pet peeve -- as petty as it sounds. I've considered using a different logging libraries, but the truth is, all I want is this feature in the standard library.

Let me explain myself.

I find the date in the following logs:

2021/12/15 19:39:13 Listening on :8080
2021/12/15 19:39:15 Received termination signal, attempting to gracefully shut down
2021/12/15 19:39:15 http: Server closed
2021/12/15 19:39:15 Shutting down janitor   
2021/12/15 19:39:16 Shutting down

significantly more distracting than this:

2021-12-15 19:39:13 Listening on :8080
2021-12-15 19:39:15 Received termination signal, attempting to gracefully shut down
2021-12-15 19:39:15 http: Server closed
2021-12-15 19:39:15 Shutting down janitor   
2021-12-15 19:39:16 Shutting down

I find it easier to read because - doesn't leave the ambiguity that / does with 1 and 7, and after having used Go for a long time and scrolling through millions of lines of logs, ambiguity or not, / makes my eyes pause for slightly longer than - would.

Furthermore, the separator for time is also :, which, like -, has a much smaller max character height than /, making it less visually distracting.

Making the change is extremely trivial -- I don't mind taking care of it, in fact, I'd love to -- but I'd like to know if there are any objections to it. From what I've seen, the log package is extremely barebone, and rightfully so, but I really think that in term of UX, having an easier-to-read date format in the standard library log package would go a long way.

FWIW, if I was the only person impacted, I would have wanted the package to use - as the date separator by default, alas, this would surely break more than one libraries.

Relevant

#6095: Unlike this issue, I actually think that having the timestamp follow ISO8601 would make the whole timestamp even less readable. All I'm interested in is adding a flag to use - instead of / for the date.

[josharian]

It seems to me that if we were going to do something like this, we should provide an API to replace the entire time format string.