CodeSOD: This is the Endian

Anyone who's ever needed to write cross-platform code in C or C++ knows that TRWTF is endianness. Your options are either to use a lot of platform specific preprocessor macros, or to coerce all of your data into your own specific format, for portability.

Adam H's company took the latter approach, implementing a ByteWriter class. It was relatively easy to use, with code that looked something like this:

 byte* tempData = new byte[128]; ByteWriter* writer = ByteWriter::Instance(); writer->Initialize(tempData); writer->PutInt32(someIntValue); writer->PutInt32(someOtherIntValue); writer->PutByte(someByteArray);

At this point, tempData will hold your integers with the correct endianness, regardless of platform. But gee, that call to ByteWriter::Instance sure looks odd. Is that some kind of factory method? If so, that call to Initialize is weird. Let's go to the implementation of the class"

 class ByteWriter { private: int _index; byte* _data; static ByteWriter *_instance = 0; ByteWriter() {} public: void Initialize(byte* data) { _index = 0; _data = data; } void PutInt32(int32_t w) { PutInt16((int32_t)(w & 0x0000FFFF)); PutInt16((int32_t)((w & 0xFFFF0000) >> 16)); } void PutInt16(int16_t w) { PutByte((byte)(w & 0x00FF)); PutByte((byte)((w & 0xFF00) >> 8)); } void PutByte(byte b) { _data[_index] = b; _index++; } static ByteWriter *Instance() { if (!_instance) _instance = new ByteWriter(); return _instance; } }

And this is what drew Adam into this code in the first place- it was breaking any time it was touched by multiple threads, and of course it was. This is a classic example of the "Unnecessary Singleton" design pattern, commonly implemented by people who have skimmed the "Gang of Four" book, and needed to prove they knew what a design pattern was during an interview.

Unfortunately for Adam, this bit code highlights the problem, but:

This isn't the source verbatim, as TRWTF here is hard to nail down to one snippet, but it should be clear with a few pieces. (It also means that I may have messed up C++ syntax)

It's going to be much more complicated for him to actually fix.

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