Sometimes I have a question about how something works in a tied variable. This one-liner lets me use "perl -de 0" to interactively test how tied variables behave.

For example, when I was curious about how keys and each interact with a tied hash, I did this:

 > perl -de 0
# ...
  DB<1> sub AUTOLOAD { print STDERR "$AUTOLOAD( @_ ): "; eval <STDIN> 
+}

  DB<2> tie %h,'main'
main::TIEHASH( main ): bless []

  DB<3> x tied %h
0  main=ARRAY(0x1c81a88)
     empty array
  DB<4> print 0+keys %h
main::FIRSTKEY( main=ARRAY(0x1c81a88) ): 'hello'
main::NEXTKEY( main=ARRAY(0x1c81a88) hello ): 'goodbye'
main::NEXTKEY( main=ARRAY(0x1c81a88) goodbye ):
2
  DB<5> while( my($k,$v)= each %h ) { warn "$k=>$v\n"; keys %h if !$v 
+}
main::FIRSTKEY( main=ARRAY(0x1c81a88) ): 'hello'
main::FETCH( main=ARRAY(0x1c81a88) hello ): 'hi'
hello=>hi
main::NEXTKEY( main=ARRAY(0x1c81a88) hello ): 'goodbye'
main::FETCH( main=ARRAY(0x1c81a88) goodbye ): 'bye'
goodbye=>bye
main::NEXTKEY( main=ARRAY(0x1c81a88) goodbye ): 'reset'
main::FETCH( main=ARRAY(0x1c81a88) reset ): 0
reset=>0
main::FIRSTKEY( main=ARRAY(0x1c81a88) ):

  DB<6> q
main::DESTROY( main=ARRAY(0x1c81a88) ):

 > exit
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Note how keys in a void context causes the each iterator to start over at FIRSTKEY() [without having to bother the object] while keys in a scalar context has to ask the object for every key just so that it can count them.

sub AUTOLOAD { print STDERR "$AUTOLOAD( @_ ): "; eval <STDIN> }
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