Nit: Use $object->{ISBN} instead ... $$object{ISBN} can lead to subtle bugs.

I meant to ask before, and forgot: can you elaborate on this? Assuming for the moment that $object is a real reference here, not a "symbolic reference" string (we'll pretend for the moment that I was using strict; if the program were complex enough to span more than about half a dozen subroutines I would be), what subtle bugs would (or could) my syntax lead to? At first I thought you meant that someone might write $object{foo} by mistake instead of $$object{foo}, but then I realised warnings or strict either one would catch that, so you must be talking about something more subtle... but what? 

sub H{$_=shift;while($_){$c=0;while(s/^2//){$c++;}s/^4//;$
v.=(' ','|','_',"\n",'\\','/')[$c]}$v}sub A{$_=shift;while
($_){$d=hex chop;for(1..4){$pl.=($d%2)?4:2;$d>>=1}}$pl}$H=
"16f6da116f6db14b4b0906c4f324";print H(A($H)) # -- jonadab

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In reply to That Nit (was Re: Parallel structures are NOT maintainable) by jonadab
in thread using references as keys in a hash. by habit_forming

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