I'd like to offer you not to ask particular questions about some tricks in Perl or any particular programming language. As someone told usualy programmers concentrate on special tasks and don't remember exact syntax's tricks of such huge language like Perl.
in reply to A Perl aptitude test
As I know and I eagerly welcome that lot of companies test IQ of potential employees by providing them test with some abstract language, also a person is tested should be provided with documentation of syntax of that abstract language.
In addition you may provide to develop some application using perl or whatever else with computer and documentation.