The trick is that variables created by "my" are not available until the next statement, as documented in perlsub: 
The declared variable is not introduced (is not visible)
until after the current statement. Thus,

    my $x = $x;

can be used to initialize a new $x with the value of the 
old $x, and the expression

    my $x = 123 and $x == 123

is false unless the old $x happened to have the value 123 .

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In reply to Re: Using an undefined value as a hashref by itub
in thread Using an undefined value as a hashref by talexb

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