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Done adding Catch with return of Promise #77

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Done adding Catch with return of Promise #77

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a98e940
Done adding Catch with return of Promise
mystikxkemix Jun 12, 2018
16d9cfb
Change new Catch Method
mystikxkemix Jun 13, 2018
04f7d76
Add new tests
mystikxkemix Jun 13, 2018
cf07808
Fix Promise Test
mystikxkemix Jun 14, 2018
32a1228
Merge branch 'master' of github.com:Real-Serious-Games/C-Sharp-Promis…
mystikxkemix Aug 22, 2018
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27 changes: 27 additions & 0 deletions Promise.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,8 @@ public interface IPromise<PromisedT>
/// </summary>
IPromise<PromisedT> Catch(Func<Exception, PromisedT> onRejected);

IPromise<ConvertedT> Catch<ConvertedT>(Func<Exception, IPromise<ConvertedT>> onRejected);
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This needs the <summary>...</summary> comment on it so that a description of how the method works shows up in IntelliSense.

This should also return IPromise<PromisedT>, not IPromise<ConvertedT>. This is because Catch doesn't always run, so if we try to convert the type of the promise in the catch handler, we have no way of knowing after the catch whether the type is the original PromisedT or the ConvertedT.

promiseReturningAnInt()
    .Then<int>(value => value + 1) 
    .Catch<string>(ex => Promise.Resolved<string>(ex.Message))
    .Then<???>(arg => /* no way to know whether arg should be an int or a string */);

The only case where you can return a different type of promise in the rejected handler is in the overload of .Then where both the resolved and rejected handlers are guarenteed to return the same type - see Promise.cs line 75


/// <summary>
/// Add a resolved callback that chains a value promise (optionally converting to a different value type).
/// </summary>
Expand Down Expand Up @@ -580,6 +582,31 @@ public IPromise<PromisedT> Catch(Func<Exception, PromisedT> onRejected)

return resultPromise;
}

public IPromise<ConvertedT> Catch<ConvertedT>(Func<Exception, IPromise<ConvertedT>> onRejected) {
var resultPromise = new Promise<ConvertedT>();
resultPromise.WithName(Name);

Action<Exception> rejectHandler = ex =>
{
try
{
onRejected(ex)
.Then(
chainedValue => resultPromise.Resolve(chainedValue),
callbackEx => resultPromise.Reject(callbackEx)
);
}
catch (Exception callbackEx)
{
resultPromise.Reject(callbackEx);
}
};

InvokeHandler(rejectHandler, this, rejectionException);

return resultPromise;
}

/// <summary>
/// Add a resolved callback that chains a value promise (optionally converting to a different value type).
Expand Down
20 changes: 20 additions & 0 deletions Promise_NonGeneric.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,8 @@ public interface IPromise
/// </summary>
IPromise Catch(Action<Exception> onRejected);

IPromise<ConvertedT> Catch<ConvertedT>(Func<Exception, IPromise<ConvertedT>> onRejected);
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Same as above


/// <summary>
/// Add a resolved callback that chains a value promise (optionally converting to a different value type).
/// </summary>
Expand Down Expand Up @@ -671,6 +673,24 @@ public IPromise Catch(Action<Exception> onRejected)

return resultPromise;
}

public IPromise<ConvertedT> Catch<ConvertedT>(Func<Exception, IPromise<ConvertedT>> onRejected) {
var resultPromise = new Promise<ConvertedT>();
resultPromise.WithName(Name);

Action<Exception> rejectHandler = ex =>
{
onRejected(ex)
.Then(
chainedValue => resultPromise.Resolve(chainedValue),
callbackEx => resultPromise.Reject(callbackEx)
);
};

InvokeRejectHandler(rejectHandler, this, rejectionException);

return resultPromise;
}

/// <summary>
/// Add a resolved callback that chains a value promise (optionally converting to a different value type).
Expand Down