[shared_preferences] full api redesign with DataStore and cache-less interface

[tarrinneal]

Full rework for shared_preferences, allows user to decide whether to use cache or be fully async and pull direct from the platform.

fixes https://github.com/flutter/flutter/issues/123078 fixes https://github.com/flutter/flutter/issues/133098 fixes https://github.com/flutter/flutter/issues/65145 fixes https://github.com/flutter/flutter/issues/64739

[tmpfs]

Can I please add to this that support for preferences separated by namespace would be very useful. My app supports multiple accounts and I want the preferences to be distinct for each account.

I could achieve this be prefixing every key but that is awkward and error prone. I then looked into using setPrefix() but I can't overwrite the prefix after getInstance() had been called which I need for my app.

If calling setPrefix() instead rebuilt (or switched) the cache then I think I would be able to use shared_preferences.

As it stands I have no choice but to roll my own preference handling which is a shame when shared_preferences is very nearly there for my requirements.

[stuartmorgan]

Can I please add to this that support for preferences separated by namespace would be very useful. My app supports multiple accounts and I want the preferences to be distinct for each account.

Please file a new issue to propose new functionality, so that discussion here can remain focused on the review.

[tmpfs]

Can I please add to this that support for preferences separated by namespace would be very useful. My app supports multiple accounts and I want the preferences to be distinct for each account.

Please file a new issue to propose new functionality, so that discussion here can remain focused on the review.

@stuartmorgan issues are not enabled for this repository, should I open the issue on the main flutter repository?

[stuartmorgan]

@stuartmorgan issues are not enabled for this repository, should I open the issue on the main flutter repository?

https://github.com/flutter/packages#issues

[hellohuanlin]

@tarrinneal do you have a design doc that I can take a look before reviewing it?

[tarrinneal]

@tarrinneal do you have a design doc that I can take a look before reviewing it?

https://docs.google.com/document/d/1DNhUYIJaDA10g2cOqipKyPuPkgL_FYPfgkF9Coqcc6k/edit

Might have changed the design a bit since I wrote it.

[tarrinneal]

We should probably start brainstorming actual names in parallel with the rest of the review. Maybe AsyncSharedPreferences and CachedSharedPreferences?

CachedSharedPreferences seems incorrect. SharedPreferencesWithCache? I'm fine with either.

[goderbauer]

(triage): I spoke to @tarrinneal last week and he said this is still on his radar.

[tarrinneal]

It looks like there was a force-push since my last review, so GitHub won't show me the incremental diffs.

There hasn't, probably just a github bug. I think the things that needed review were pretty clear though, since you'd already covered everything

[stuartmorgan]

I was able to coax it into showing me some of the recent diffs if I selected them by hand.

[tarrinneal]

@stuartmorgan last chance if you want to do another pass on this now that it's just the front end.

[tarrinneal]

Looks like tests are passing (besides mac flake), going to mark as auto merge!

[auto-submit[bot]]

auto label is removed for flutter/packages/5210, due to - The status or check suite Mac_arm64 ios_platform_tests_shard_1 master has failed. Please fix the issues identified (or deflake) before re-applying this label.

[xVemu]

setMockInitialValues is missing for SharedPreferencesWithCache

[tarrinneal]

setMockInitialValues is missing for SharedPreferencesWithCache

You can set the cache manually when instantiating SharedPreferencesWithCache so there is no need for that method.