Avoid runtime function type check in lazily created singleton creator functions #574
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/cc @mraleph wdyt? |
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@mraleph Who would be good to review this? |
rakudrama
reviewed
Feb 4, 2022
| T Function() fun) { | ||
| final oldMaker = _defaultMakers[fun]; | ||
| if (oldMaker != null) { | ||
| return oldMaker as _SingletonMaker<T>; |
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To avoid check in dart2js production code, use an implicit downcast via:
return oldMaker as dynamic;
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Thanks for the suggestion. Done.
mraleph
reviewed
Feb 7, 2022
| /// For generated code only. | ||
| static T $_defaultFor<T extends GeneratedMessage>(T Function() createFn) => | ||
| _defaultMakerFor<T>(createFn)(); | ||
| class _SingletonMaker<T extends GeneratedMessage> { |
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You should probably add a comment here explaining why we go this route (e.g. explain that we want to avoid any type checks against a function type and hence you an object container for functions).
mkustermann
commented
Feb 7, 2022
| /// For generated code only. | ||
| static T $_defaultFor<T extends GeneratedMessage>(T Function() createFn) => | ||
| _defaultMakerFor<T>(createFn)(); | ||
| class _SingletonMaker<T extends GeneratedMessage> { |
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In order to avoid a runtime function type check (which is complex to perform and is implemented inefficiently in the Dart VM atm) we restructure the code that creates frozen singleton creator functions.
Issue #573