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dart-archive / observe

Support for marking objects as observable, and getting notifications when those objects are mutated
https://pub.dartlang.org/packages/observe
BSD 3-Clause "New" or "Revised" License
13 stars 6 forks source link

@MirrorsUsed errors using ObservableList.length when passed through dart2js #53

Closed DartBot closed 9 years ago

DartBot commented 9 years ago

Issue by butlermatt Originally opened as dart-lang/sdk#15283

Trying to get the length of an ObservableList, works in Dart. When compiled to Javascript my console shows errors:

Uncaught Unsupported operation: Can't use 'length' in reflection because it is not included in a @­MirrorsUsed annotation. reports.html_bootstrap.dart.js:2414 wrapException reports.html_bootstrap.dart.js:2414 _rootHandleUncaughtError__closure.call$0 reports.html_bootstrap.dart.js:9488 _asyncRunCallback reports.html_bootstrap.dart.js:6871 TimerImpl_internalCallback0.call$0 reports.html_bootstrap.dart.js:2039 invokeClosure_closure.call$0 reports.html_bootstrap.dart.js:3576 _IsolateContext.eval$1 reports.html_bootstrap.dart.js:1363 _callInIsolate reports.html_bootstrap.dart.js:1111 invokeClosure reports.html_bootstrap.dart.js:2555 (anonymous function) reports.html_bootstrap.dart.js:2575 Uncaught Error: Unsupported operation: Can't use 'length' in reflection because it is not included in a @­MirrorsUsed annotation. reports.html_bootstrap.dart.js:4087 Stack Trace: Error     at Object.wrapException (http://<myHost>/reports/reports.html_bootstrap.dart.js:2414:13)     at Object.throwInvalidReflectionError (http://<myHost>/reports/reports.html_bootstrap.dart.js:2077:11)     at JSInvocationMirror._getCachedInvocation$1 (http://<myHost>/reports/reports.html_bootstrap.dart.js:3322:11)     at JsInstanceMirror._invoke$4 (http://<myHost>/reports/reports.html_bootstrap.dart.js:5589:31)     at JsInstanceMirror.getField$1 (http://<myHost>/reports/reports.html_bootstrap.dart.js:5609:17)     at InvokeObserver._updateSelf$1 (http://<myHost>/reports/reports.html_bootstrap.dart.js:22622:74)     at InvokeObserver.ExpressionObserver._observe$1 (http://<myHost>/reports/reports.html_bootstrap.dart.js:22264:10)     at InvokeObserver.ExpressionObserver._invalidate$1 (http://<myHost>/reports/reports.html_bootstrap.dart.js:22251:10)     at IdentifierObserver.ExpressionObserver._invalidate$1 (http://<myHost>/reports/reports.html_bootstrap.dart.js:22254:10)     at IdentifierObserver__updateSelf_closure.call$1 (http://<myHost>/reports/reports.html_bootstrap.dart.js:22497:19)

My Environment: Dart Editor version 1.0.0_r30338 (DEV) Dart SDK version 1.0.0.7_r30338 Linux 64-Bit.

Packages: Polymer (and company) 0.9.0.

DartBot commented 9 years ago

Comment by butlermatt

Updated some libraries (html5lib, observe, shadow_dom) to 0.9.1 and error persists.

DartBot commented 9 years ago

Comment by butlermatt

This appears to be caused in my polymer-element markup where I was using the polymer expression:

<template if="{{ list.length == 0 }}"> ... </template>

I know recently observe was updated to 0.9.1 which supposedly fixed issues with list.isEmpty and isNotEmpty from within polymer expressions but it appears the .length property was not similarly updated.

For what it's worth, I have observe 0.9.1 and encounter the same error using the list.isEmpty property as well. (However polymer and polymer expressions are still 0.9.0 as polymer expressions 0.9.1 has not yet landed on pub (polymer 0.9.1 has but requires 0.9.1 so it's not a valid upgrade path).

DartBot commented 9 years ago

Comment by kasperl

Not sure if this is an issue with ObservableList or dart2js.

Added Library-Observe, Triaged labels.

DartBot commented 9 years ago

Comment by sigmundch

Hey Matt, what is the type of 'list' in that expression (ObservableList or normal List?). Does this continue to happen if you get all at version 0.9.1 (now that they are actually uploaded)?

DartBot commented 9 years ago

Comment by butlermatt

I think what happened was that the variable list is initially passed a normal List, but then I reassign it as an ObservableList. However obviously it fails soon as the List is passed to it, even before I have a chance to convert it to an ObservableList. I have a work around in place assigning the value from within dart code as opposed to within Polymer Expressions so feel free to close as wontfix/invalid.

DartBot commented 9 years ago

Comment by jmesserly

Thanks Matt.

I'm still investigating ways to make this better. You should be able to include things like List.length too.

https://code.google.com/p/dart/issues/detail?id=15334

Added AssumedStale label.

DartBot commented 9 years ago

Comment by anders-sandholm

Removed Library-Observe label. Added Pkg-Observe label.