Custom Publishers/Subscribers

📚 Official Books Combine: Asynchronous Programming with Swift
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Hi,

After reading your book (v0.3), I felt inspired to use Combine in some of my newer projects. Fast forward some weeks and I have written several custom publishers/operators/subscribers.

Since at the time I struggled finding working examples for custom publishers, I have decided to gather some of them in a Github repo in case it is helpful to someone.

Cheers and keep up the great work. I can wait to read the last chapters.

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Feedback like this really brightens my day, thank you for taking the time to write us! That repo looks really useful and shared it onwards to the https://combine.community slack and twitter. The final version of the books should arrive within days with the rest of the chapters :+1:t3:

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Thank you for your kind works and for sharing.

I am really looking forward finishing the book. It is really good, so far.

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This is great. Thank you!

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This is wonderful, @dehesa! Congratulations for this achievement and many more to come!

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A little update on this project:

There are now custom subscribers on the repo using backpressure, which I find myself using more and more (e.g. it is quite an interesting tool to control the amount of in-flight API calls).

Also I have added some interesting operators/publishers such as:

  • retry on error and wait a given amount of seconds between attempts.
    apiPublisher.retry(on: queue, interval: [1, 3, 5])
  • handleEnd to execute a side-effect (exactly once) for any kind of completion (whether successful completion, failure, or cancel) so you can always clean up state.
    upstream.handleEnd { /* clean up */ }

Once one creates some custom publishers/subscribers, it is quite surprising how mechanical (and fast) the creation can be if you distill the core competences. I have extracted the basic states of any Combine entity on a property wrapper that can be easily used if you decide to create your own custom Combine publishers or subscribers.

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@dehesa Congratulations and keep up the good work! :]

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