Suggest final keyword for new Widget classes by default

[loveoverflowcom]

Use case

Developers create new widgets frequently. Many of these widgets are not designed for inheritance.

By suggesting final, we prevent accidental subclassing, making the widget safer and signaling the intended use clearly.

Improves code readability and maintainability by indicating immutability at the class level.

Could potentially optimize performance, as Dart may optimize final classes better in certain scenarios.

Proposal

Currently, when creating a new Widget class in Flutter, IDEs and templates do not suggest using the final keyword for the class.

Most Widgets are not intended to be subclassed, and marking them as final improves code safety and can have minor performance benefits.

The proposal is to add a suggestion or template update in Flutter tools and IDEs so that when developers create a new Widget, the final keyword is recommended or auto-inserted.

[bkonyi]

Removing team-tool and assigning to team-devexp since this isn't a tool specific issue and there's no team-packages (@stuartmorgan-g can you adjust the labels if this isn't right?)

Hi @loveoverflowcom, thanks for the proposal!

This is something that would belong in package:flutter_lints, which specifies our default set of lint rules for Flutter projects.

@srawlins, would you happen to know if there's an existing lint for this?

[srawlins]

I don't believe there is any existing lint rule for this.

[stuartmorgan-g]

assigning to team-devexp since this isn't a tool specific issue and there's no team-packages

team-ecosystem is the team for most packages, but:

This is something that would belong in package:flutter_lints, which specifies our default set of lint rules for Flutter projects.

flutter_lints isn't a linter, it's a collection of suggested lint rules. Implementing a new lint rule isn't within the scope of flutter_lints.