Isegoria

In exploring the art of Making Wrong Code Look Wrong, Joel Spolsky looks at what Hungarian notation originally meant:

It looked like Hungarian, and Simonyi was from Hungary, thus the name. In Simonyi’s version of Hungarian notation, every variable was prefixed with a lower case tag that indicated the kind of thing that the variable contained [ e.g. rwMax].

I’m using the word kind on purpose, there, because Simonyi mistakenly used the word type in his paper, and generations of programmers misunderstood what he meant.

If you read Simonyi’s paper closely, what he was getting at was the same kind of naming convention as I used in my example above where we decided that us meant “unsafe string” and s meant “safe string.” They’re both of type string. The compiler won’t help you if you assign one to the other and Intellisense won’t tell you bupkis. But they are semantically different; they need to be interpreted differently and treated differently and some kind of conversion function will need to be called if you assign one to the other or you will have a runtime bug. If you’re lucky.

Simonyi’s original concept for Hungarian notation was called, inside Microsoft, Apps Hungarian, because it was used in the Applications Division, to wit, Word and Excel. In Excel’s source code you see a lot of rw and col and when you see those you know that they refer to rows and columns. Yep, they’re both integers, but it never makes sense to assign between them. In Word, I’m told, you see a lot of xl and xw, where xl means “horizontal coordinates relative to the layout” and xw means “horizontal coordinates relative to the window.” Both ints. Not interchangeable. In both apps you see a lot of cb meaning “count of bytes.” Yep, it’s an int again, but you know so much more about it just by looking at the variable name. It’s a count of bytes: a buffer size. And if you see xl = cb, well, blow the Bad Code Whistle, that is obviously wrong code, because even though xl and cb are both integers, it’s completely crazy to set a horizontal offset in pixels to a count of bytes.
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But then something kind of wrong happened.

The dark side took over Hungarian Notation.

Nobody seems to know why or how, but it appears that the documentation writers on the Windows team inadvertently invented what came to be known as Systems Hungarian.

Somebody, somewhere, read Simonyi’s paper, where he used the word “type,” and thought he meant type, like class, like in a type system, like the type checking that the compiler does. He did not. He explained very carefully exactly what he meant by the word “type,” but it didn’t help. The damage was done.

Apps Hungarian had very useful, meaningful prefixes like “ix” to mean an index into an array, “c” to mean a count, “d” to mean the difference between two numbers (for example “dx” meant “width”), and so forth.

Systems Hungarian had far less useful prefixes like “l” for long and “ul” for “unsigned long” and “dw” for double word, which is, actually, uh, an unsigned long. In Systems Hungarian, the only thing that the prefix told you was the actual data type of the variable.

This was a subtle but complete misunderstanding of Simonyi’s intention and practice, and it just goes to show you that if you write convoluted, dense academic prose nobody will understand it and your ideas will be misinterpreted and then the misinterpreted ideas will be ridiculed even when they weren’t your ideas.

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