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kallentu/variance_usage_fields.dart

Last active December 19, 2019 18:14
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variance_usage_fields.dart
class Reader<out T> {
// Compile-time error: Can't use 'out' type variable 'T' in an 'in' position.
T readableWritableValue;
// OK
final T readableValue;
}
class Writer<in T> {
// Compile-time error: Can't use 'in' type variable 'T' in an 'out' position.
T readableWritableValue;
// Compile-time error: Can't use 'in' type variable 'T' in an 'out' position.
final T readableValue;
}
class ReaderWriter<inout T> {
// Both OK
T readableWritableValue;
final T readableValue;
}
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