This example works for allow_mixing.
http://www.plantuml.com/plantuml/png/Iyp9oI-FpysioCnBvqhEIImkLaZBppUivj9MoCmhKGX9pItWgkKgIaqkISnBpqa5IHfnWGW5NJkmIYiha1e0
@startuml
allow_mixing
class foo1{
+ int Temp
}
rectangle foo2
foo2 -> foo1::Temp
@enduml
The below one is not working for allow_mixing with Syntax Error
http://www.plantuml.com/plantuml/png/Iyp9oI-FpysioCnBvqhEIImkLaZBppUivj9MoCmhKGX9pItWgkKgIaqkISnBpqbLK0BA6YafLAC96Ii1LO6a57Jjm0POMO6q0W00
@startuml
allow_mixing
class foo1{
+ int Temp
}
rectangle "foo2" {
rectangle "foo3"
}
foo2 -> foo1::Temp
@enduml