Add SliverGrid.list convenience constructor

[ahmeddhus]

This PR adds a new SliverGrid.list convenience constructor that accepts a List<Widget> children parameter, providing a cleaner API compared to manually creating SliverChildListDelegate.

What was added

The constructor uses SliverChildListDelegate internally and follows the same pattern as existing convenience constructors like SliverGrid.count and SliverGrid.extent. This addresses the use case where developers want to create sliver grids with predefined widget lists without the verbosity of manually constructing the delegate.

Before/After comparison

Before:

SliverGrid(
  gridDelegate: gridDelegate,
  delegate: SliverChildListDelegate([widget1, widget2, widget3]),
)

After:

SliverGrid.list(
  gridDelegate: gridDelegate,
  children: [widget1, widget2, widget3],
)

Implementation details

• Added SliverGrid.list constructor in packages/flutter/lib/src/widgets/sliver.dart
• Constructor accepts List<Widget> children and all necessary delegate configuration parameters
• Uses SliverChildListDelegate internally for consistent behavior
• Added comprehensive test coverage in packages/flutter/test/widgets/slivers_test.dart

Issue addressed

Fixes: #173018

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• I followed the [breaking change policy] and added [Data Driven Fixes] where supported.
• All existing and new tests are passing.

[gemini-code-assist]

Code Review

This pull request introduces a SliverGrid.list convenience constructor, which simplifies creating a SliverGrid from a list of widgets. The implementation is clean and follows existing patterns in the framework. The accompanying tests cover the basic functionality and edge cases well.

My main feedback is to enhance the documentation for the new constructor to fully align with the Flutter Style Guide by adding a code example and documenting all parameters. This will improve its usability for other developers.

[justinmc]

FYI @loic-sharma since you opened the issue asking for this (#173018).

[loic-sharma]

This looks good to me - thanks for the wonderful contribution!

[ahmeddhus]

This looks good to me - thanks for the wonderful contribution!

Thank you! Excited to keep contributing 🙌

[victorsanni]

Are these two newlines intentional?

[ahmeddhus]

Thanks, that was unintentional. I’ve fixed it 👍

[loic-sharma]

@ahmeddhus Looks like there are some formatting issues, can you run dart format?

See: https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8705948798842944625/+/u/run_test.dart_for_analyze_shard_and_subshard_None/stdout

[ahmeddhus]

@ahmeddhus Looks like there are some formatting issues, can you run dart format?

See: https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8705948798842944625/+/u/run_test.dart_for_analyze_shard_and_subshard_None/stdout

Fixed 👍🏾

[victorsanni]

LGTM. Thanks for the PR

[auto-submit]

autosubmit label was removed for flutter/flutter/173925, because - The status or check suite Google testing has failed. Please fix the issues identified (or deflake) before re-applying this label.