Proposal: Upgrading examples from using io/util (once 1.17 ships)

[selahaddinh]

Hey everyone,
As you may know, there are talks of deprecating io/util for go v1.16.
More on this can be found:
golang/go#40025
go-critic/go-critic#1019
golang/go#42026

I think, upgrading the examples from using io/util would be beneficial for newcomers to learn the state-of-art practices.

[eliben]

Sounds good, given that the replacements work on the current and previous version (e.g. if they go in right now, on versions 1.15 and 1.14 at least). Feel free to send a PR

[selahaddinh]

I believe, this needs to wait version 1.17 then.

[selahaddinh]

just leaving here for archive purpose, from https://tip.golang.org/doc/go1.16

Discard => io.Discard
NopCloser => io.NopCloser
ReadAll => io.ReadAll
ReadDir => os.ReadDir (note: returns a slice of os.DirEntry rather than a slice of fs.FileInfo)
ReadFile => os.ReadFile
TempDir => os.MkdirTemp
TempFile => os.CreateTemp
WriteFile => os.WriteFile```

[eliben]

Go 1.17 will be released in August 2021. At that point we should be able to safely replace uses of ioutil with os, where applicable.

At this time, gobyexample uses the following functions from ioutil in examples:

• WriteFile
• ReadDir
• ReadAll
• TempFile
• TempDir
• ReadFile

[eliben]

Since we keep getting duplicate reports, I went ahead and created #374 which implements this - that PR will be updated and reviewed/landed once Go 1.17 ships in August 2021.