Document expected behavior for APIs that expect a return type of Type? #56500

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1. TahaTesser

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   d: examplesSample code and demosSample code and demos

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   frameworkflutter/packages/flutter repository. See also f: labels.flutter/packages/flutter repository. See also f: labels.

   on May 7, 2020
2. goderbauer commented on May 13, 2020

   

   goderbauer

   on May 13, 2020

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   Can you make a suggestion as to what you would like us to add to the documentation? Looking at it, it seems pretty clear. You're supposed to provide a widget type that's typically used. The one that's typically used would have a specific type, not a generic one.
3. goderbauer

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   on May 13, 2020
4. znjameswu commented on May 14, 2020

   

   znjameswu

   on May 14, 2020

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   Due to this Dart limitation, we need to manually create a getType function to retrieve the type (in this answer). This workaround requires quite some serious Dart knowledge, primarily reified generics, for user (especially users from JS or Java background, whose generics use type erasure and have very different behavior).

   For future APIs designed in this pattern, it may be helpful to add a line of comment about the best solution for generic types, until this Dart limitation has been solved.
5. no-response

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6. TahaTesser

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   easy fix

   on Jul 31, 2020
7. markusaksli-nc

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   passed first triage

   on Sep 17, 2020
8. goderbauer

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   P2Important issues not at the top of the work listImportant issues not at the top of the work list

   on Aug 23, 2022
9. Hixie

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   documentation

   on Jul 5, 2023
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11. Hixie

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    passed first triage

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12. Hixie commented on Jul 13, 2023

    

    Hixie

    on Jul 13, 2023

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    debugTypicalAncestorWidgetClass is the only property or method I could find that returns a type where this might be an issue. I've added the following to the documentation:

      ///                                                                                                                                                                        
      /// ## Implementations                                                                                                                                                     
      ///                                                                                                                                                                        
      /// The returned type should be a subclass of `RenderObjectWidget`.                                                                                                        
      ///                                                                                                                                                                        
      /// ```dart                                                                                                                                                                
      ///   @override                                                                                                                                                            
      ///   Type get debugTypicalAncestorWidgetClass => FrogJar;                                                                                                                 
      /// ```                                                                                                                                                                    
      ///                                                                                                                                                                        
      /// If the "typical" parent is generic (`Foo<T>`), consider specifying either                                                                                              
      /// a typical type argument (e.g. `Foo<int>` if `int` is typically how the                                                                                                 
      /// type is specialized), or specifying the upper bound (e.g. `Foo<Object?>`).                                                                                             

    (It's now possible to create a generic literal, FWIW.)
13. Hixie

    self-assigned this

    on Jul 13, 2023
14. Hixie

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    waiting for PR to land (fixed)A fix is in flightA fix is in flight

    on Jul 13, 2023
15. auto-submit

    closed this as completedin #130530on Jul 19, 2023
16. auto-submit

    added a commit that references this issue on Jul 19, 2023

    Add implementation advice to debugTypicalAncestorWidgetClass (#130530)

    ...

    07cdf37
17. LouiseHsu

    added a commit that references this issue on Jul 31, 2023

    Add implementation advice to debugTypicalAncestorWidgetClass (flutter…

    ...

    8c0b738
18. github-actions commented on Aug 2, 2023

    

    github-actionsbot

    on Aug 2, 2023

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    This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.
19. github-actions

    locked as resolved and limited conversation to collaborators on Aug 2, 2023