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Subscribe to the source of an ObservableAsPropertyHelper immediately and add a deferSubscription parameter #1061

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Merged
flagbug merged 1 commit into from
Apr 12, 2016
Merged

Subscribe to the source of an ObservableAsPropertyHelper immediately and add a deferSubscription parameter #1061

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45 changes: 43 additions & 2 deletions ReactiveUI.Tests/ObservableAsPropertyHelperTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,7 @@ public void OAPHShouldProvideLatestValue()
var input = new Subject<int>();

var fixture = new ObservableAsPropertyHelper<int>(input,
_ => { }, -5, sched);
_ => { }, -5, scheduler: sched);

Assert.Equal(-5, fixture.Value);
(new[] { 1, 2, 3, 4 }).Run(x => input.OnNext(x));
Expand All @@ -86,13 +86,54 @@ public void OAPHShouldProvideLatestValue()
Assert.Equal(4, fixture.Value);
}

[Fact]
public void OAPHShouldSubscribeImmediatelyToSource()
{
bool isSubscribed = false;

var observable = Observable.Create<int>(o =>
{
isSubscribed = true;
o.OnNext(42);
o.OnCompleted();

return Disposable.Empty;
});

var fixture = new ObservableAsPropertyHelper<int>(observable, _ => { }, 0);

Assert.True(isSubscribed);
Assert.Equal(42, fixture.Value);
}

[Fact]
public void OAPHDeferSubscriptionParameterDefersSubscriptionToSource()
{
bool isSubscribed = false;

var observable = Observable.Create<int>(o =>
{
isSubscribed = true;
o.OnNext(42);
o.OnCompleted();

return Disposable.Empty;
});

var fixture = new ObservableAsPropertyHelper<int>(observable, _ => { }, 0, true);

Assert.False(isSubscribed);
Assert.Equal(42, fixture.Value);
Assert.True(isSubscribed);
}

[Fact]
public void OAPHShouldRethrowErrors()
{
var input = new Subject<int>();
var sched = new TestScheduler();

var fixture = new ObservableAsPropertyHelper<int>(input, _ => { }, -5, sched);
var fixture = new ObservableAsPropertyHelper<int>(input, _ => { }, -5, scheduler: sched);
var errors = new List<Exception>();

Assert.Equal(-5, fixture.Value);
Expand Down
41 changes: 35 additions & 6 deletions ReactiveUI/ObservableAsPropertyHelper.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,14 +34,21 @@ public sealed class ObservableAsPropertyHelper<T> : IHandleObservableErrors, IDi
/// changes, typically this will call the ViewModel's
/// RaisePropertyChanged method.</param>
/// <param name="initialValue">The initial value of the property.</param>
/// <param name="deferSubscription">
/// A value indicating whether the <see cref="ObservableAsPropertyHelper{T}"/>
/// should defer the subscription to the <paramref name="observable"/> source
/// until the first call to <see cref="Value"/>, or if it should immediately
/// subscribe to the the <paramref name="observable"/> source.
/// </param>
/// <param name="scheduler">The scheduler that the notifications will be
/// provided on - this should normally be a Dispatcher-based scheduler
/// (and is by default)</param>
public ObservableAsPropertyHelper(
IObservable<T> observable,
Action<T> onChanged,
T initialValue = default(T),
IScheduler scheduler = null) : this(observable, onChanged, null, initialValue, scheduler) {}
bool deferSubscription = false,
IScheduler scheduler = null) : this(observable, onChanged, null, initialValue, deferSubscription, scheduler) {}

/// <summary>
/// Constructs an ObservableAsPropertyHelper object.
Expand All @@ -54,6 +61,12 @@ public ObservableAsPropertyHelper(
/// changes, typically this will call the ViewModel's
/// RaisePropertyChanging method.</param>
/// <param name="initialValue">The initial value of the property.</param>
/// <param name="deferSubscription">
/// A value indicating whether the <see cref="ObservableAsPropertyHelper{T}"/>
/// should defer the subscription to the <paramref name="observable"/> source
/// until the first call to <see cref="Value"/>, or if it should immediately
/// subscribe to the the <paramref name="observable"/> source.
/// </param>
/// <param name="scheduler">The scheduler that the notifications will be
/// provided on - this should normally be a Dispatcher-based scheduler
/// (and is by default)</param>
Expand All @@ -62,6 +75,7 @@ public ObservableAsPropertyHelper(
Action<T> onChanged,
Action<T> onChanging = null,
T initialValue = default(T),
bool deferSubscription = false,
IScheduler scheduler = null)
{
Contract.Requires(observable != null);
Expand All @@ -83,7 +97,7 @@ public ObservableAsPropertyHelper(

_lastValue = initialValue;
_source = observable.StartWith(initialValue).DistinctUntilChanged().Multicast(subj);
if (ModeDetector.InUnitTestRunner())
if (!deferSubscription)
{
_inner = _source.Connect();
_activated = 1;
Expand Down Expand Up @@ -126,7 +140,7 @@ public void Dispose()
/// (and is by default)</param>
public static ObservableAsPropertyHelper<T> Default(T initialValue = default(T), IScheduler scheduler = null)
{
return new ObservableAsPropertyHelper<T>(Observable.Never<T>(), _ => {}, initialValue, scheduler);
return new ObservableAsPropertyHelper<T>(Observable.Never<T>(), _ => {}, initialValue, false, scheduler);
}
}

Expand All @@ -137,6 +151,7 @@ static ObservableAsPropertyHelper<TRet> observableToProperty<TObj, TRet>(
IObservable<TRet> observable,
Expression<Func<TObj, TRet>> property,
TRet initialValue = default(TRet),
bool deferSubscription = false,
IScheduler scheduler = null)
where TObj : IReactiveObject
{
Expand All @@ -154,7 +169,7 @@ static ObservableAsPropertyHelper<TRet> observableToProperty<TObj, TRet>(
var ret = new ObservableAsPropertyHelper<TRet>(observable,
_ => This.raisePropertyChanged(name),
_ => This.raisePropertyChanging(name),
initialValue, scheduler);
initialValue, deferSubscription, scheduler);

return ret;
}
Expand All @@ -168,6 +183,12 @@ static ObservableAsPropertyHelper<TRet> observableToProperty<TObj, TRet>(
/// <param name="property">An Expression representing the property (i.e.
/// 'x => x.SomeProperty'</param>
/// <param name="initialValue">The initial value of the property.</param>
/// <param name="deferSubscription">
/// A value indicating whether the <see cref="ObservableAsPropertyHelper{T}"/>
/// should defer the subscription to the <paramref name="observable"/> source
/// until the first call to <see cref="Value"/>, or if it should immediately
/// subscribe to the the <paramref name="observable"/> source.
/// </param>
/// <param name="scheduler">The scheduler that the notifications will be
/// provided on - this should normally be a Dispatcher-based scheduler
/// (and is by default)</param>
Expand All @@ -178,10 +199,11 @@ public static ObservableAsPropertyHelper<TRet> ToProperty<TObj, TRet>(
TObj source,
Expression<Func<TObj, TRet>> property,
TRet initialValue = default(TRet),
bool deferSubscription = false,
IScheduler scheduler = null)
where TObj : IReactiveObject
{
return source.observableToProperty(This, property, initialValue, scheduler);
return source.observableToProperty(This, property, initialValue, deferSubscription, scheduler);
}

/// <summary>
Expand All @@ -193,6 +215,12 @@ public static ObservableAsPropertyHelper<TRet> ToProperty<TObj, TRet>(
/// <param name="property">An Expression representing the property (i.e.
/// 'x => x.SomeProperty'</param>
/// <param name="initialValue">The initial value of the property.</param>
/// <param name="deferSubscription">
/// A value indicating whether the <see cref="ObservableAsPropertyHelper{T}"/>
/// should defer the subscription to the <paramref name="observable"/> source
/// until the first call to <see cref="Value"/>, or if it should immediately
/// subscribe to the the <paramref name="observable"/> source.
/// </param>
/// <param name="scheduler">The scheduler that the notifications will be
/// provided on - this should normally be a Dispatcher-based scheduler
/// (and is by default)</param>
Expand All @@ -204,10 +232,11 @@ public static ObservableAsPropertyHelper<TRet> ToProperty<TObj, TRet>(
Expression<Func<TObj, TRet>> property,
out ObservableAsPropertyHelper<TRet> result,
TRet initialValue = default(TRet),
bool deferSubscription = false,
IScheduler scheduler = null)
where TObj : IReactiveObject
{
var ret = source.observableToProperty(This, property, initialValue, scheduler);
var ret = source.observableToProperty(This, property, initialValue, deferSubscription, scheduler);

result = ret;
return ret;
Expand Down