The Old New Thing

Practical development throughout the evolution of Windows.

Latest posts

How can I know when a window has processed a message that I posted to it?
Nov 25, 2024
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How can I know when a window has processed a message that I posted to it?

Raymond Chen
Raymond Chen

Best would be to have it tell you.

In C++, how can I make a default parameter be the this pointer of the caller?, revisited
Nov 22, 2024
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In C++, how can I make a default parameter be the this pointer of the caller?, revisited

Raymond Chen
Raymond Chen

Expanding on the previous pattern.

How can I detect which menu my item was invoked from?
Nov 21, 2024
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How can I detect which menu my item was invoked from?

Raymond Chen
Raymond Chen

Just give them all different IDs. But this might itself by an XY problem.

How do I determine whether Explorer is showing or hiding file extensions?
Nov 20, 2024
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How do I determine whether Explorer is showing or hiding file extensions?

Raymond Chen
Raymond Chen

You can ask, but maybe you're asking the wrong question.

A wrinkle in how Windows 95 setup bootstrapped its initial GUI step
Nov 19, 2024
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A wrinkle in how Windows 95 setup bootstrapped its initial GUI step

Raymond Chen
Raymond Chen

Getting access to the common controls that don't exist until Windows 95.

The operations for reading and writing single elements for C++ standard library maps
Nov 18, 2024
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The operations for reading and writing single elements for C++ standard library maps

Raymond Chen
Raymond Chen

Breaking down the options.

How do I put a non-copyable, non-movable, non-constructible object into a <CODE>std::optional</CODE>?
Nov 15, 2024
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How do I put a non-copyable, non-movable, non-constructible object into a std::optional?

Raymond Chen
Raymond Chen

Taking advantage of the conversion operator.

Solving the puzzle of trying to put an object into a <CODE>std::optional</CODE>
Nov 14, 2024
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Solving the puzzle of trying to put an object into a std::optional

Raymond Chen
Raymond Chen

How do I set a value? Let me count the ways.

The puzzle of trying to put an object into a <CODE>std::optional</CODE>
Nov 13, 2024
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The puzzle of trying to put an object into a std::optional

Raymond Chen
Raymond Chen

The C++ standard library template type has one of two states. It could be empty (not contain anything), or it could contain a . Suppose you start with an empty . How do you put a into it? One of my colleagues tried to do it in what seemed to be the most natural way: Use the assignment operator. Unfortunately, the assignment failed to compile: I asked for the rest of the error message, because the details will explain what the compiler tried to do (and why it couldn't). It's long, but we'll walk through it. The compiler is showing its work. It's showing you all the possible overloaded assignment opera...