空流上的Observable.Min / Max抛出异常？ [英] Observable.Min/Max throw Exception on Empty Stream?

问题描述

如果在运行min / max时流为空，是否会引发异常？

Is the expected behavior to throw an exception if the stream is empty when running min/max?

除了使用minBy / maxBy之外，我如何测试以确保存在值如果序列有可能为空，则在热流上运行min / max？

Other than using minBy/maxBy how can I test to ensure values exists and run min/max on a hot stream if there is potential for the sequence to be empty?

推荐答案

你还希望看到什么？当你得到一个空序列。国际海事组织你正在采取一组许多并将其减少到一组1.如果该组是空的，单个值是什么？

What are you hoping to see when you get an empty sequence. IMO you are taking a set of many and reducing it to a set of 1. If the set is empty, what would the single value be?

如果你有答案那么甜！

我能想到的2个选项是：

2 options I can think of are:

1）如果源序列为空，则输出序列应为空

1) If the source sequence is empty, then the output sequence should be empty

var source = Observable.Empty<int>();
//source.Min() causes OnError(InvalidOperationEx)

//Empty sequence with MinBy
source.MinBy(x=>x)....

//Empty sequence with Catch/Swallow
source.Min()
      .Catch((InvalidOperationException ex)=>Observable.Empty<int>())

2）如果为空（0，null等等），则返回默认的最小值

2) Return a default min value if empty (0, null, etc...)

var defaultValue = 0;
var source = Observable.Empty<int>();
//source.Min().Dump("min");//OnError(InvalidOperationEx)

//Catch error and continue with default value.
source.Min()
	  .Catch((InvalidOperationException ex)=>Observable.Return<int>(defaultValue))
	  .Dump("catch");

所以是的，MinBy做出与Min不同的事情有点奇怪。但是这里有一些选择。

So yeah, it is a bit weird that MinBy does something different to Min. But here are some options for you.

Lee

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