Re: how to organize source code for a complete software? Thanks!

[stefan-lucks@see-the.signature]

> I am new to Ada, and I just have some experiences in using Fortran.
> 
> When using Fortran, I generally put each subroutine or function in a separate
> file, e.g., dot.for for dot product of two vectors. Then a main.for that call
> the necessary subroutine or functions. It seems to be rational.
> 
> When I using Ada, I don't know how to do. There are procedure, function,
> package, package body, and so on (with different file extension, e.g., ada,
> adb, ads, ...). And there is no main program.

1. Any parameterless procedure, which is not "local" inside another 
   function/procedure or inside a package, can be the main program.

2. As a rule of thumb for beginners: Put your auxiliary subprograms (in 
   Ada: a subprogram is either a function or a procedure) and the requited 
   type definition into packages. Write a single parameterless main 
   procedure as the "main" procedure, but give it a meaningful name 
   ("Solve_Linear_Equations" or "Delete_File" rather than "Main"). Put 
   that procedure into a file of its own. 

2a. Note that a package consists of a specification and an implementation, 
    which are usually put into TWO different files (e.g., "name.ads" for 
    the spec and "name.adb" for the implementation body). 

2b. When you are more advanced in programming in Ada, you may sometimes 
    want to compile "separate" subprograms without wrapping them into 
    packages.  

3. Compile the main procedure (e.g., by calling "gnatmake" if you use the 
   gnat Ada compiler) -- your compiler will know which packages it needs 
   to compile. 

> And, please, if you like, point me a small, complete open source software in
> Ada (not a library or package). I should be compiled and run. I just hope to
> learn how to start a software in Ada by example.

Examples: 
  <http://rosettacode.org/wiki/Linear_congruential_generator#Ada> 
  <http://rosettacode.org/wiki/Ternary_logic#Ada>

The linear congruential example would consist of three files: 
  1. the specification "lcg.ads",
  2. the implementation "lcg.adb", and
  3. the main program "run_lcgs.adb". 
(These are the gnat/gcc naming conventions, look into your compiler 
documentation if you use another compiler.)

As an easy exercise for the reader, try to figure out which three files 
the ternary logic example would consist of. 


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------ Stefan Lucks   --  Bauhaus-University Weimar  --   Germany  ------
               Stefan dot Lucks at uni minus weimar dot de
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