An extra edge case: 
 perl -le'while($a = 0){print "$a ok\n"; last }'    # 
 perl -le'while($a = 1){print "$a ok\n"; last }'    # prints 1 ok

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But the "implicit test for defined" is built into the while( ) by language design, there is no extra magic about that in any context?

In reply to Re^4: <STDIN> not initializing $_ by stiller
in thread <STDIN> not initializing $_ by carol

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