refactor!: Make descendants return an eagerly collected snapshot list - #4009
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spydon wants to merge 1 commit into
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refactor!: Make descendants return an eagerly collected snapshot list#4009spydon wants to merge 1 commit into
spydon wants to merge 1 commit into
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luanpotter
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Aug 16, 2026
| void _remove(Component parent) { | ||
| parent._internalChildren.remove(this); | ||
| for (final component in _collectDescendants()) { | ||
| for (final component in _collectDescendants(reversed: true)) { |
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why not use the public descendants here?
luanpotter
reviewed
Aug 16, 2026
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| testWithFlameGame('descendants() iterator is lazy', (game) async { | ||
| testWithFlameGame('descendants() supports early stopping', (game) async { |
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this is no longer a feature of descendants but rather just how dart streams work, this test is misleading as the list is now eagerly collected (arguably it was wrong to begin with bc even before it was not testing what it was intending to)
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Description
descendants()was a lazysync*generator, which allocates an iterator per tree level and pays a delegation chain walk per element. After #3981 it was the last generator-shaped traversal of the component tree; this PR makes it delegate to the same_collectDescendantscollection pass, so there is only one traversal shape left to care about.The method now returns a
List<Component>that is an eagerly collected snapshot of the tree at the moment of the call. This means the whole subtree is always traversed (early stopping no longer saves traversal work), and iterating while adding or removing components is safe instead of surfacing aConcurrentModificationError.Checklist
docsand added dartdoc comments with///.examplesordocs.Breaking Change?
Migration instructions
Most call sites need no changes, since
ListimplementsIterable. Overrides ofdescendantsmust update their return type fromIterable<Component>toList<Component>. Code that relied on the lazy iteration semantics (early stopping to avoid traversing large trees, or catchingConcurrentModificationErroron mutation during iteration) now gets a full-tree snapshot instead; query methods such asfirstWherestill stop early, they just iterate an already collected list.Related Issues
Relates to #3957