Rx framework – IObservable<T>.Concat

Yan Cui

I help clients go faster for less using serverless technologies.

Yet another extension method to combine two observable collections, this time we have IObservable<T>.Concat which is very similar to IObservable<T>.Merge, but crucially, when you concatenate one observable collection to another, the subscription to the second observable collection happens after the first had completed! Here’s a quick illustration of how the two methods differ:

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As you’ve probably guessed already, the Concat method requires the observable collections to be merged to be of the same type.

Again, you can either invoke it as an extension method:

var zs = xs.Concat(ys);

or you can invoke it as static method on more than two observable collections:

var zs = Observable.Concat(xs, ys, us, vs);

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