Read up on writing your own sorting function. Also, take a look at the Schwartzian Transform. (Writing your own sorting functions is in the same section as sorting in the Camel book. If you have the 3rd edition, look at pp. 789 - 793.) The Schwartzian Transform (aka ST) is searchable in the box at the top of your screen.

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We are the carpenters and bricklayers of the Information Age.

The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.