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Yes you see it, nice!
Indeed the await foreach is enumerating events asynchronously! 
modified 18-Dec-21 23:15pm.
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This feels to me like something they'll have a better pattern for in .NET 8.
Still, it's cool. I've been looking for an application of IAsyncEnumerable, but I have yet to come up with much that's very compelling. Most of the time, since it's sequential and I can't return items in parallel anyway, each item depends on completing the previous one, no? If so, you only really get the benefit of the asynchronocity on the final item, unless I'm missing something - which I probably am.
If I'm reading a forward only stream for example, the next byte i read depends on me first having fetched the previous byte, which means i'm waiting on each element. Again, unless I'm missing something.
So I'm still trying to wrap my head around the async foreach.
Real programmers use butterflies
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I think you missed something......
To answer the last question first, the only (very good) practical usage I found for IAsyncEnumrable so far is to enumerate events asynchronously. Events, as you know, happens later, much later, if at all!
So, to your first question:
Let's detail the mouse drag operation
When mouse down happen, I want to wait on next mouse move. I could have written code like that await NextMouseMoveasync()
This would have required lots of boilerplate code. Instead I started my work with reactive, an observable library, which let you manipulate, compose, analyze and action event stream (operators documentation). Really help for that kind of stuff.
It's great, but doesnt use async and the callback syntax for action on event can be complicated when you do lots of stuff. Anyway I much prefer async code to callback code. It's the same thing, but feels more.. straightforward? easier to read?
I can live with the funny exception callstack, but I so much more enjoy the improved code layout.
So next step was to turn this IObservable event stream into an IAsyncEnumerable, here just use the extension method ToAsyncEnumerable().
and voila:
when I write
await foreach (var event Observable.Merge(MouseMove, MouseUp).ToAsynEnumerable())
I am asynchronously waiting for either next mouse move of mouse up, and handling it in the foreach body.
It's 100% asynchronous, what is enumerated here are mouse events, the foreach body is run on each mouse move event, which happens like once every 0.05 seconds, at best! And maybe not at all!
Does my explanation help shed some light?
Perhaps I should have trimmed my initial sample a bit.... mm..  
modified 19-Dec-21 0:03am.
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Yeah, I mean, it's advantageous when *one* item is going to take a long time, but I just don't run into that in the real world a lot. I understand why *you* are using it *here*, but I can't think of many places I'd actually need it outside replacing UI eventing code.
Real programmers use butterflies
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ha well.. this code is all about event stream.
If you have to manipulate multiple events together it talks to you, otherwise it doesn't.
modified 19-Dec-21 0:44am.
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Everything I touch over the past 48 hours just turns to garbage, codewise.
I think it's just a run of bad luck but it's super frustrating.
I try to get my SPI driver working, and I have massive timing problems.
I try getting sound working on my NES emulator and as soon as I enable it, boom - reboot loop
*sigh*
I'm afraid to do paying work right now because of it. I hate this.
Real programmers use butterflies
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Don't worry, people who are paid to do work, introduce bugs in their paid time, true story! 
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Yeah but the next thing I have on my plate for work is bugfixing!
Real programmers use butterflies
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You can't fix bugs if you don't write a few first.
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Such wisdom! 
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You've obviously never had the misfortune of being part of the team like the one I was, a few years back.
It would've been fine if I was the silly monkey writing all the bugs...
Hate to imagine what being a medical doctor feels like!
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Good morning,
honey the codewitch wrote: I try to get my SPI driver working, and I have massive timing problems.
I'm looking at your st7789 code[^] and I don't see how it could ever work reliably in its current state. But it also looks like a relatively easy fix.
The datasheet[^] has a section labled 'Parallel Interface Timing Characteristics' which has a table containing the min/max wait and hold times. Why can't you just add a delay parameter to your command and data functions[^] and use os_delay_us() to wait for the period + hold.
Or you could just try taking the largest wait time and always wait for the maximum. For example, the largest write wait time I see in the st7789 datasheet appears to be 16ns.
Best Wishes,
-David Delaune
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Here's the thing.
If I insert pauses between all my commands, my code will be the only code on the Internet that does that.
Seriously.
This code is basically copied, pasted, and the function names cleaned up - from a working library.
Now, I can insert delays to make my code slower.
But I darn well want to know why my code is the only one that needs delays.
Edit: I put delays everywhere. Same problem. *headdesk*
Real programmers use butterflies
modified 19-Dec-21 6:23am.
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Hi,
honey the codewitch wrote: If I insert pauses between all my commands, my code will be the only code on the Internet that does that.
Are you sure about that? Look how the reference library you copied code from uses SPI_FREQUENCY[^] Also look at the busy-wait around the SPIBUSY[^] bits.
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That's not an extra pause. That's just polling for the SPI transfer to complete, and my code does it too.
Here's how I write a byte:
*_spi_mosi_dlen = 7;
*_spi_w = value;
*_spi_cmd = SPI_USR;
while (*_spi_cmd & SPI_USR);
The only difference here is I'm referencing the registers via a volatile static member - but his code does that too - look at the different #ifdef paths. Also I'm using SPI_USR which is how you poll on an ESP32. I don't think you use the busy flag on this platform. not even sure it's defined. (he has different code files for different processors)
I use the frequency as well. It's a template argument to tft_spi<>
Real programmers use butterflies
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Alright,
Well, I don't see anything else that stands out. You might need to figure this one out yourself. Unless you can find someone with similar hardware to take a look. 
Best Wishes,
David Delaune
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Yeah, that's where I'm at. I didn't figure on any help here, or I would have posted it in programming questions. I was just venting.
Real programmers use butterflies
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Ok,
I thought I saw someone in the esp32 sub offer to test for you the other day. Maybe you should take up the offer.
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Thanks. I must have missed it. I'll recheck my posts.
Real programmers use butterflies
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I only bring this up because this post is so current (12/16/2021), succinct (18 minutes), and yet so comprehensive.
Xamarin.Forms Quickstart Deep Dive - Xamarin | Microsoft Docs
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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I appreciate things that are current, well written and relevant (IOS; Android; UWP; mobile). I gave my reason for posting it. What more do you need?
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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I used to. And hopefully I will again.
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The Kinks, A Gallon Of Gas:
The Kinks - A Gallon Of Gas - YouTube[^]
[Edit]
I remember my first time in US before about 30 years. We joinend Los Angeles up to San Francisco with a camper. We payed sometething around $1 for one gallon. In my country we received 1L for that cash 
Btw. 1 Gallon is about 3.79L
[Edit]
Currently US (google): $1 per Gallon$3.5 / Gallone
Here about: $2 per Liter
modified 18-Dec-21 15:12pm.
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Yes and before
The less you need, the more you have.
Even a blind squirrel gets a nut...occasionally.
JaxCoder.com
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