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Subroutine Prototypes Subroutine Prototypes

You may declare subroutines with an optional prototype definition

Prototypes constrain subroutine caller's arguments to match in number and type to a pre-specified definition

sub MySubroutine($\@$) { EXPR }

Only calls using the "new" style of subroutine call syntax are checked

New style calls reference subroutines without the & prefix

MySubroutine( "Hello", @foo, 12.32 );