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Puzzle: Warnings Golf

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McGlinchy, Alistair
September 1, 2004 12:34
Puzzle: Warnings Golf
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This list has been a tad quiet for a while so I thought I'd throw in a golfy puzzle.

For some reason the keys on my keyboard temporarily rearranged themselves today and a quick one-liner I was writing didn't do what I expected; in fact it did nothing at all. So I added a -w flag and I got 4 separate warnings. I thought, 4 warnings ain't good enough, I wanted more!

In a few minutes I had a 9 byte one liner that produced 7 distinct warnings when run with -w but did nothing without -w. That's 0.77 warnings per byte of code, not bad but I'm sure there's more to be found.  Sure a simple perl -we 'a' gives two warnings for one byte, but that seams a little too trivial.  

Puzzle: Write a one-liner longer than (say) 3 bytes that can improve on 0.77 distinct warnings per byte of code. The program should be -c valid, output nothing without -w and sound the alarm as much as possible with -w.

For those who like sand-traps, I suggest you shouldn't count multiple messages that give the same warning for different quoted strings. For example  perl -we "a,b" gives four warnings (1.3/byte) but only scores two distinct ones (0.66/byte). Nor can you count the same warning on multiple lines of input.  The following will hopefully give a true distinct warnings score.
	perl -we 'yourcode'  2>&1 | perl -ne 's/\042.*\042//;s/at -e.*$//;$x{$_}++;END{print 0+keys%x}' 



PS please excuse the \042 in the regex I was chopping between Cygwin and cmd.exe and " in cmd is a complete #£&^%$^!


D:\>perl -ce "%$A==$@,z"
-e syntax OK

D:\>perl -e "%$A==$@,z"

D:\>perl -we "%$A==$@,z"
Unquoted string "z" may clash with future reserved word at -e line 1.
Useless use of numeric eq (==) in void context at -e line 1.
Useless use of a constant in void context at -e line 1.
Name "main::A" used only once: possible typo at -e line 1.
Use of uninitialized value in hash dereference at -e line 1.
Argument "" isn't numeric in numeric eq (==) at -e line 1.
Use of uninitialized value in numeric eq (==) at -e line 1.



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