`ExpressionNode`s were always single-subscriber and making them use `IObservable<>` meant that we had to have extra allocations in order to return `IDisposable`s. Instead of using `IObservable` use a simpler `Subscribe`/`Unsubscribe` pattern. This saves a bunch more memory.
Previously it wasn't clear which constructor on `InstancedBinding` must be called for a particular binding mode. Refactored the constructors:
- We now have a single public ctor which takes an `ISubject`, as a subject can be used for all binding modes.
- Instanced bindings with other sources such as single values and `IObservables` are now constructed via static methods which only allow the correct sources for that binding mode
1. Fixed some tests to expect `BindingNotification`s to be returned on a broken binding chain.
2. Changed logging of `BindingNotification`s - log at `Warning` level (instead of `Error`) except when the binding chain is broken at the root, in which case log at `Information` level. Do this to prevent flooding the output window when initializing.
It's a bad idea - if you put say a `3` into a `BindingNotification`, that `int` will get boxed and then put into a `WeakReference`, which means that the `3` can get GC'd. That's not a desireable behavior!
In Release build in main Avalonia assemblies (couldn't do it in
Avalonia.Markup.Xaml due to warnings in OmniXaml). To do this, fixed a
number of warnings.
- Don't log an error when the target for the root ExpressionNode is
null. This is usually because the `DataContext` hasn't been set up yet
and it spewed a load of useless error messages.
- Add a Description field to `ExpressionObserver` that can be used in
the case of e.g. #control bindings to record the whole expression (with
the "#control" part) rather than just the part tracked by the
`ExpressionObserver`.
OneTime bindings were failing in BindingTest because the initial binding
error was being counted as the single value to transfer. Don't do this
with OneTime bindings - only transfer valid values.
Jeremy Koritzinsky
Steven Kirk
Steven Kirk
Steven Kirk