Re: Array Literals?

[johnherro@aol.com (John Herro)]

cosc19z5@Bayou.UH.EDU (Spasmo) writes:
> What exactly is the difference between using
> Int_Array' ( ), and Int_Array ( )?
     The ' with ( ) indicates *qualification*.  That is, you're telling
the compiler what the type is, because, perhaps, it's not obvious from the
literal or the aggregate.  The ( ) without the ' indicates *conversion*
from one type to another.
     For example, suppose your Ada compiler implements type Long_Integer,
and you have
     J : Integer;
     procedure Display(Item : in Integer);
     procedure Display(Item : in Long_Integer);
Then writing Display(3); is ambiguous, so you would *qualify* the literal
and write Display(Long_Integer'(3));.  On the other hand, if you want to
*convert* J to Long_Integer, you use ( ) without the ' and write, for
example, Display(Long_Integer(J));
     Sometimes you need to qualify an enumeration literal.  This example
is from my Ada Tutor program (available for download at the Web and FTP
sites below my signature):
     type Rainbow_Color is (Red, Orange, Yellow, Green, Blue, Indigo,
Violet);
     type Traffic_Light Color is (Red, Amber, Green);
     procedure Display(Item : in Rainbow_Color);
     procedure Display(Item : in Traffic_Light_Color);
Now the compiler can handle Display(Violet); and Display(Amber);, but
requires the qualification in Display(Rainbow_Color'(Red));.  I hope this
helps.
- John Herro
Software Innovations Technology
http://members.aol.com/AdaTutor
ftp://members.aol.com/AdaTutor
     A doctor, a civil engineer, and a software engineer were arguing
about who has the oldest profession.  The doctor said, "God made Eve from
the rib of Adam, a surgical operation."  The civil engineer said, "Before
He did that, God made order from chaos and put the planets in motion, a
feat of civil engineering."  The software engineer replied, "Wait a
minute!  Where do you think the chaos came from?"