Brethren

Looking yesterday at a listing of revision dates I saw 

3-AUG-2007
8-AUG-2007
1-OCT-2007
1-OCT-2007-RevA
1
2

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Hmm, that 1 and 2 look odd...

After sleuthing, I ran (something like) 

 ($foo, $bar, $date) = qw(fooa bar7 1-OCT-2007-RevA);
  print "++$foo ++$bar ++$date\n"

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and saw 
  foob bar8 1

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Which puzzled me greatly until I found the auto-increment docs
The auto-increment operator has a little extra builtin magic to it. If you increment a variable that is numeric, or that has ever been used in a numeric context, you get a normal increment. If, however, the variable has been used in only string contexts since it was set, and has a value that is not the empty string and matches the pattern /^a-zA-Z*0-9*\z/ , the increment is done as a string, preserving each character within its range, with carry:
OK. Problem explained. But here I ask the Perl Monks for explanation. Why? Why limit the magic to strings that match the pattern? When is it ever better to return '1' than the incremented string?

throop

updated with minor cleanup

In reply to String increment - reasoning by throop

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