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in sum: a Win 10 update has, evidently, made all my user folders readonly, and permissions can't be changed.
note: i post this here because i think the issue goes beyond specific code used here to illustrate the issue.
Lo and behold, some serialization code using DataContractSerializer (worked fine two months ago) that creates a file on the desktop throws a "file not found exception" when creating a new FileStream.
using (var writer =
new FileStream(filename1, FileMode.Create, FileAccess.Write))
{
dcs.WriteObject(writer, instance);
}So:
1 verify the directory exists. i know the File does not exist because i delete it if it does exist.
2 try using File.Create to create the Stream, experiment with all the various params to 'new FileStream'
3 scratch my head
4 a suspicion dawns that permissions on the Directory have changed. yep: iit's readonly: i change permissions on the Directory: they immediately revert back to readonly.
5 Turns out that a Win update has made everything on my primary drive readonly.
6 go google and find ... yep ... other people are having the same problem after an update: [^]
7 try the various remedies suggested in the above link: they don't work.
8 post on Lounge
9 scratch head
«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali
modified 14-Sep-19 0:11am.
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Bill,
You would need to enable or disable controlled folder access[^] to prevent this from happening again in the future.
The problem here is that the operating system needs to protect 80 year old grandmothers, your kids, your lawyer, the scientists in your office building while annoying most of the software engineers and power users. 
Best Wishes,
-David Delaune
Scientiæ de conservata veritate.
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Thanks, David, you nailed it !
Disabling the ":controlled access" setting, and re-booting: now, i can write to the file.
i had not thought of a possible Win Defender change as the demon at work, here; my long-term sub to EmsiSoft AV just expired, and i guess Win Defeater took over. Interesting i didn't see any Google hits mentioning Win Defender in my searching.
Also, interesting, the Desktop folder i am using still shows up as readonly, and undoing that setting does not persist: it goes back to readonly 
Please come to Chiang Mai, and let me take you for a bowl of the famous northern Thai noodles called kao soi (your choice of beef, chicken, or fish; it's customarily a halal dish, so no pork in the really old establishment i go to)
cheers, Bill
«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali
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Hmmmm,
BillWoodruff wrote: Please come to Chiang Mai, and let me take you for a bowl of the famous northern Thai noodles called kao soi (your choice of beef, chicken, or fish; it's customarily a halal dish, so no pork in the really old establishment i go to)
The last time I ate Thai noodles... I was out with 5 friends. Then the friend from New Zealand managed to get poked in the eye with an asian chopstick. Pretty soon we'll have to call them 4 eyes.
Best Wishes,
-David Delaune
Scientiæ de conservata veritate.
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BillWoodruff wrote: note: i post this here because i think the issue goes beyond specific code used here to illustrate the issue.
And IMHO it is right posted.
I need to upgrade lappie and was a "ok, nice to know" for me
M.D.V. 
If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
Rating helpful answers is nice, but saying thanks can be even nicer.
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Flail?
Sent from my Amstrad PC 1640
Never throw anything away, Griff
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
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Yup 
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I'm considering writing a B+ tree in C# but in order to make it worthwhile it needs to be disk backed.
My question is, and it's a weird one but i have my reasons:
Did Btrieve use separate files for its indexes versus its data or was it all in one file?
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
modified 13-Sep-19 16:39pm.
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I remember it very good. Everything was in _one_ file.
It does not solve my Problem, but it answers my question
modified 19-Jan-21 21:04pm.
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Thanks! You just helped me understand ISAM a lot better than you maybe know you did. 
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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You are welcome I don't think this was a important help. Btw way some details e.g. here: Btrieve Files[^]
It does not solve my Problem, but it answers my question
modified 19-Jan-21 21:04pm.
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it was because it told me how records are managed and a bit about how they're stored. Thanks for the format. I'm not looking to read BTrieve files but I'll save the link because it may answer questions that come up.
My primary interest in ISAM is in how it maps a B+ tree structure to disk, because that's what I'd need to do with a B+tree implementation.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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honey the codewitch wrote: My primary interest in ISAM is in how it maps a B+ tree structure to disk, because that's what I'd need to do with a B+tree implementation.
You could always take a look at either gnu GDBM or Oracle-Berkeley DB to see how they solved the issue. Unless that's cheating, or you want to avoid any license issues.
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yeah i don't even want to touch anything GNU
besides, that code is mature. it's not so easy to dissect.
I'd rather either start from scratch, or from something simple.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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k5054 wrote: You could always take a look at either gnu GDBM or Oracle-Berkeley DB to see how they solved the issue. Unless that's cheating, or you want to avoid any license issues.
Those DBM libraries simply work in a contiguous memory region and write the entire database back to disk when saved. That's why everyone avoided key-value-store (NoSQL is the new buzzword) databases for over a decade. When RAM became cheap and you build a server with terabyte of RAM... the old things became new again.
By the way... let's give credit to the inventing author... Ken Thompson[^] who wrote the first DBM implementation... sometime in the late 1970's. It's not even mentioned in his wikipedia bio... I wonder if anyone will remember that in 30 years.
Best Wishes,
-David Delaune
Scientiæ de conservata veritate.
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I do. The worlds DOS speed demon data systems used it.
RDP (Resort Data Processing) software was one. Ran on Novell Servers.
And we made a lot of money then.
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honey the codewitch wrote: Did Btrieve use separate files for its indexes versus its data or was it all in one file?
On systems with dual floppies, we sometimes implemented the index on one file one one floppy and the data on another. But those were dedicated turnkey systems on a 32KB machine with 720KB floppies (dual sided.) 
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That's actually a smart way to do it in any case - even if you had the space on one disk.
The reason is, as long as the floppy controller supported it, you could have both spindles working at once, and so you don't have as much I/O lag.
The same principle applies in modern databases and is why good database design will partition frequently accessed tables onto their own HD "spindles" - either physical spindles, or just logical like with an SSD - point is, you read from more than one drive at once.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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I think my new pet peeve are those sites that change their Window title to "(1) New Message" at 1Hz so that, even when they are a background tab they are still annoying you.
Make mental blacklist note, close tab, get on with my work.
cheers
Chris Maunder
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Never mind a mental blacklist - add 'em to your adblock list and never see it again.
There aren't many sites out there that are indispensable - CodeProject is obviously one of those - so if they are annoying, block 'em, maybe tell 'em why, and move on.
Sent from my Amstrad PC 1640
Never throw anything away, Griff
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
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I just ported a splay tree function from typescript to C# painlessly and it made my code faster.
this is amazingly and wonderfully not like javascript.
it's a wonder everyone is not using it instead of raw JS.
When I was growin' up, I was the smartest kid I knew. Maybe that was just because I didn't know that many kids. All I know is now I feel the opposite.
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Yeah - I've found TypeScript and never want to go back.
Our own @Pete-OHanlon has written a book on the topic. It's a lifesaver.
cheers
Chris Maunder
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