state declares a lexically scoped variable, just like my.
However, those variables will never be reinitialized, contrary to
lexical variables that are reinitialized each time their enclosing block
is entered.
See Persistent Private Variables in perlsub for details.
state variables are enabled only when the use feature "state"
pragma
is in effect, unless the keyword is written as CORE::state
.
See also feature.