chore: update rust edition to 2021

[marcoieni]

No description provided.

[simonsan]

I would probably adapt all the pages + examples first to the 2021 edition before setting this?

Meaning, we should change it exactly like you did but also check which idioms, patterns are still needed or useful. Setting 2021 edition in the book should also mark our milestone of being patterns 2021 edition IMHO.

[marcoieni]

also check which idioms, patterns are still needed or useful.

I think that nothing changes with our content if the reader has 2018 or 2021 as the edition field of their crate.
If you are suggesting reviewing all the book...this is going to take a lot of time, which I would love to have, but I don't :/

Instead, by merging this PR now, we make sure that the rust examples of this book can be compiled with rust edition 2021 👍

Also, does it makes sense to release the patterns 2021 edition at the end of 2022? 😛

OT: it was around this period we started maintaining this project together. So happy "anniversary"! Thanks for everything you have done for this project and happy holidays 🎄

[simonsan]

also check which idioms, patterns are still needed or useful.

I think that nothing changes with our content if the reader has 2018 or 2021 as the edition field of their crate. If you are suggesting reviewing all the book...this is going to take a lot of time, which I would love to have, but I don't :/

Instead, by merging this PR now, we make sure that the rust examples of this book can be compiled with rust edition 2021 👍

Also, does it makes sense to release the patterns 2021 edition at the end of 2022? 😛

OT: it was around this period we started maintaining this project together. So happy "anniversary"! Thanks for everything you have done for this project and happy holidays 🎄

Happy anniversary as well! :) I'm a bit off the grid the next days, so will answer next week, when I had time to think about it properly! 😅

[simonsan]

With the translations refactor coming in, I want to discuss a change that is also related to this PR. Will open an issue.

EDIT: related issue #356