Add Dart / Flutter framework support policy

[mtrezza]

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Current Limitation

The Parse SDK is missing a policy that defines when support of a Dart / Flutter framework version should be dropped.

Feature / Enhancement Description

Add a support policy depending on the LTS policy by the framework publishers, or if there is no such policy, according to community best practice.

[parse-github-assistant]

Thanks for opening this issue!

• 🎉 We are excited about your ideas for improvement!

[mtrezza]

Dart and Fluter don't seem to have a LTS policy. It seems like an easy concept to just not issue a LTS policy, but it doesn't address the issue LTS is trying to solve, which is helping developers (and dependency maintainers like us) to plan how much time they have until their app becomes incompatible with its frameworks.

Someone could open a PR today that makes the Parse SDK require the latest release of Dart and Flutter. We probably wouldn't merge it because it would force developers to make their app compatible with the latest Dart / Flutter release in order to use the latest version of the Parse SDK. That again will lower adoption of the latest Parse SDK release among developers, which means we'll get less feedback on newer releases, etc. It's the fundamental issue LTS is addressing.

• Interestingly Dart doesn't follow semver, as the docs say:

  Minor version numbers might introduce breaking changes.

• The Dart release table shows that the release cycle varies by +/- 2 months. Approx. every 4 month we have a new breaking release.

• I think we can assume that an increment of the lower bound of the supported Dart or Flutter framework is a breaking change as it makes our SDK incompatible with an app that uses a version below the new lower bound.

The suggestion in #867 is to bump to Dart >= 2.17.0, which was released in 11 May 2022, basically a year ago. So maybe we can just establish a minimum support Dart version that is at least 1 year old. That would mean that a developer has 1 year to make their app compatible with the Dart framework until their app may become incompatible with the Parse SDK. LTS is usually 2 years, but if the Dart / Flutter community is used to having to keep up in shorter cycles I think we can cut this down to 1 year.

If we apply the same to the Flutter releases, it seems the version that is at least 1 year old is Flutter 3.0.0, released on 11 May 2022 which requires Dart 2.17.0. Interestingly it's the same min. Dart version we'd support according to the policy above. To account for cases in which the required Dart version is lower than what the Parse Dart SDK supports, our policy could say "Flutter version at least 1 year old, or the Flutter version that requires the lowest supported Dart version by the Parse Dart SDK, whatever is higher."

[catalunha]

Dart and Flutter are evolving fast and changes in 1 year would be too big.
Waiting 1 year would also leave many developers out of work. Because constant maintenance generates income.
I would suggest somewhere around 3 months to 6 months. This way we follow the news, we have time to implement it and the group does not run out of work.

[mtrezza]

Interesting argument. I'm not sure whether developer income should be a deciding factor. The factor that seems critical is how much time a developer has until the app needs to be made compatible with newer Dart / Flutter frameworks. If we say 3 (or soon 6 months), then the Parse Dart SDK would require Dart 2.19 which is the latest Dart release, which creates the issues mentioned above.

[mbfakourii]

1 year is too long to adapt to new versions, I think even 1 month is enough because the changes in the new versions are not to the extent that many changes are needed.

I agree with @catalunha , maybe 3 months to 6 months is enough !

[mtrezza]

If we assume 3 months that means the Parse Dart SDK will require the latest "major" Dart release 2.19.0. Any developers whose app is not using at least 2.19.0 won't be able to use the SDK.

Similarly, if a developer uses another dependency that hasn't been released for Dart 2.19.0, then they won't be able to upgrade the Dart version and the Parse SDK.

Are there any Dart / Flutter version adoption stats to better understand how many developers would be affected by this?

[mbfakourii]

@mtrezza
Consider this if the user does not migrate to the new Dart, but the package migrates. It is still possible to use the new package in the project with the old Dart! (I tested)

That is, if the user uses sdk: ">=2.12.0 <3.0.0 in his project, but our package uses sdk: ">=2.17.0 <3.0.0. The user can still use the package that uses the new sdk: ">=2.17.0 <3.0.0!

[mtrezza]

That's a good point. How is it even possible that the Parse Dart SDK pubspec currently says:

 environment:
  sdk: ">=2.12.0 <3.0.0"

For the Dart framework a minor version may contain breaking changes. So we don't even know yet whether the Parse SDK will be compatible with Dart 2.20.0, do we?

It seems to me that our CI is lacking a dart matrix. We are currently testing the SDK for architectures (macOS, Linux, Windows), but all the tests run with the single Dart SDK version 2.19.6.

To check compatibility we'd need to test with all minor versions within the current version range, from 2.12.x until 2.19.x, where x is the respective latest patch version. And since we cannot test unreleased versions, we cannot claim a <3.0.0 compatibility, which is essentially an open range. Instead, it should say:

environment:
  sdk: ">=2.12.0 <2.20.0"

The same goes for an app developer who cannot know whether the app will be compatible with sdk 2.20.0, so a sdk range of <3.0.0 for an app seems incorrect.

This all seems to stem from an inconsistency in the Dart world where apps and dependencies are explicitly expected to follow semver but the Dart SDK itself does not follow semver. A confusing design choice.

[Nidal-Bakir]

I will read and comment on this discussion tomorrow. I need to sleep now.
I just wanted to let everyone know that Dart 3.0.0 has been released, and there is currently an issue with the Parse Flutter SDK for anyone using Dart version 2.19.x or higher. We need to get this resolved quickly.

see the PANA score

[mtrezza]

To move ahead we could:

• merge fix: Incorrect Dart and Flutter SDKs compatibility range #867 to set the supported Dart SDK to >=2.17.0 <2.20.0
• merge fix: Remove deprecated parameter vsync from AnimatedSize #864 to remove the vsync param
• fix Add support for Dart 3 #873 with another PR where we add support for Dart SDK 3 by setting the Dart SDK range >=2.17.0 <2.20.0 || >=3.0.0 <3.1.0 and adding a CI job that actually tests with Dart 3.