The Old New Thing

Practical development throughout the evolution of Windows.

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Jun 5, 2026
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The back cover of C++: The Programming Language also raises questions not answered by the front cover

Raymond Chen

Not doing the reading.

Jun 5, 2026
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Rotation revisited: Avoiding having to calculate the gcd when doing cycle decomposition

Raymond Chen

Math is hard. Let's go counting!

Jun 4, 2026
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Rotation revisited: Cycle decomposition in clang’s libcxx

Raymond Chen

Rotating in the minimum number of steps by performing cycle decomposition.

Jun 3, 2026
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Rotation revisited: A shocking discovery about gcc’s unidirectional rotation algorithm

Raymond Chen

We've seen this before.

Jun 2, 2026
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Rotation revisited: Another unidirectional algorithm

Raymond Chen

Moving in a straight line, in a different way.

Jun 1, 2026
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The placeholder name for the Windows 8 experience was “modern”

Raymond Chen

Modern this and that.

May 29, 2026
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Sharing the result of a single Windows Runtime IAsyncOperation among multiple coroutines, part 3

Raymond Chen

A variation where we try only once.

May 28, 2026
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Sharing the result of a single Windows Runtime IAsyncOperation among multiple coroutines, part 2

Raymond Chen

Just let each person take turns trying.

May 27, 2026
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Sharing the result of a single Windows Runtime IAsyncOperation among multiple coroutines, part 1

Raymond Chen

Caching the result and knowing when the cache is valid.

May 26, 2026
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If C# and JavaScript lets me await a Windows Runtime asynchronous operation more than once, why not C++/WinRT?

Raymond Chen

A difference in philosophy.

May 25, 2026
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A hypothetical redesign of System.Diagnostics.Process to avoid confusion over properties that are valid only when you are the one who called Start

Raymond Chen

Putting them in a place that can access only if you call <CODE>Start</CODE>.

May 22, 2026
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Why do you say that a COM STA thread must pump messages if I see sample code creating STA threads and not pumping messages?

Raymond Chen

You need to pump messages when idle, but maybe you are never idle.

May 21, 2026
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How do I use Win32 structures from the Windows Runtime?

Raymond Chen

Trick question: You can't. But maybe you can fake it.

May 20, 2026
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The classic TreeView control lets me sort by name or by lParam, but why not both?

Raymond Chen

You need to arrange to get one from the other.

May 19, 2026
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What is the history of the ERROR_ARENA_TRASHED error code?

Raymond Chen

The storage control blocks were destroyed.

May 18, 2026
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Just shows that nobody cares about debugging the parity flag any more

Raymond Chen

Reported incorrectly since the day it was written.

May 15, 2026
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The case of the Create­File­Mapping that always reported ERROR_ALREADY_EXISTS

Raymond Chen

Maybe because it already exists?

May 14, 2026
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A constant-space linear-time algorithm for deleting all but the 10 most recent files in a directory

Raymond Chen

Using data structures you already knew.