Leaving all this class constructor stuff alone :
if you use shift without an array as argument it will shift from @_ (which is the array of arguments passed to a sub) when called in a sub or from @ARGV (which is the array of arguments passed to the perl program) when called from the main program body.

Thus :

myshift("testme");

sub myshift{
    print shift;
    #same result
    print shift @_;
}
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Jorg

"Do or do not, there is no try" -- Yoda