Re: Can .ads be compiled alone?

[rriehle@itu.edu]

On Saturday, November 15, 2014 11:16:50 AM UTC-8, Robert A Duff wrote:
> rriehle@itu.edu writes:
> 
> > The code you just posted is directly copied from Ada Distilled.  The
> > specification will compile just fine since it is only a specification.
> > You must compile the specification before the body.  They should be
> > compiled separately.
> 
> That depends on the compiler.  Some Ada compilers work the way you
> describe above.  GNAT does not.
> 
> Not that in GNAT, there are no requirements on compilation order.
> 
> - Bob

The code, in the example, which I originally published in my book, Ada Distilled, was compiled with GNAT.   I first compiled the specification, and then the body.   It has always been my practice to create the specification before completing the code for the body.   In fact, in the Machinery example, which is used only for pedagogic purposes, was written with the subprograms in the body stubbed-out with simply Put statements, the tested with a separate subprogram, and them finished with the completed code in the body.  I did this with all the coded examples in Ada Distilled so I could be sure that every bit of sample code would actually execute if entered exactly as I showed it in the book.   

In a future edition of Ada Distilled, in which I am collaborating with Ed Colbert, we will add examples of pre- and post-conditions, as well as other newer features of Ada 2012.