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From: Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: on package naming, should the word "_pkg" be part of it?
Date: 05 Oct 2001 09:29:31 -0400
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mike@nospam <mike_member@newsguy.com> writes:

> These sorts of things are never a problem in Java.  Do not see why Ada
> programmers always have a problem with it.
> 
> For example, in Java, the package java.awt.event contains these classes:
> 
> ActionEvent
> AdjusmentEvent
> ComponentAdapter
> ContainerAdapter
> etc...

So you are saying the convention in Java is to allways include some
type information in the name. 

How do you name something that is a list of arrays of pointers to
symbol table entries?

> The reason to having these problems with Ada is this: In Java, each
> class goes into one separate file (in general, public classes,
> etc..), and in Java, a package is not a physical thing, it is the
> name of the directory where the classes sit. i.e. there is no
> physical file that represents a package.

So what name do you give to the directory? Does it end in Package?

> In Ada, many do not like a use single package file to contain 20
> tagged records declarations in the same file with all the primitive
> operations on each one of those tagged record, and they want to have
> a one tagged record per one package. This causes the above naming
> problem.

Huh? Ahh. In Java, you put many classes in one directory. Ok. In Ada,
you can have many child packages of one parent package; same naming
conventions.

> So, I do not see why one can't do this in Ada
> 
> package Ada.awt.event is
>   type ActionEvent is tagged record .... end record;
>      -- primitive operations on ActionEvent here
> 
>   type AdjustmentEvent is tagged record .... end record;
>      -- primitive operations on AdjutsmentEvent here
> 
>   type ActionEvent is tagged record .... end record;
>      -- primitive operations on ActionEvent here
> 
>   type ComponentAdapter is tagged record .... end record;
>      -- primitive operations on ComponentAdapter here
>   
>    etc...
> end Ada.awt.event;

Perfectly legal Ada, except that the root is 'Standard', not 'Ada'. An
alternative is:

package Awt.Event is
end package;

package Awt.Event.Actions is
    type Action is tagged record ... end record;
end Awt.Event.Actions;

etc.

In Ada, you get a choice. In Java, you don't. So in that sense, Ada is
harder to use, because you have to make the choice!

> Using the above, will solve all these naming problem. But what it
> will do, is make the java package file HUGE. It is basically like
> putting all the code in those separate java class files into one big
> file.

Which is why Ada 95 has child packages.

> This means if one modifies one line of code the package file, many
> other files will have to be recompiled. No big deal, computers are
> fast these days.

Well, it is a big deal for other reasons as well; consider change
tracking. 

> After all, a package should contain related types in it, and if the
> package happened to have 20-30 related types, so they all go into
> the same one physical file (i.e. same package).

Better to put them in a package tree.

-- 
-- Stephe