Standard libraries (Was: Environment variables)

[geert@fozzie.sun3.iaf.nl (Geert Bosch)]

Robert Dewar (dewar@merv.cs.nyu.edu) wrote:
  "Very few remote target (embedded) runtime systems have environment
   variables and many operating systems do not. If they were standard
   they would be in the standard libraries. "

You could say the same of package Ada.Command_Line. The important point
is, IMHO, that a reasonable number of different platforms (Dos, Unix,
Windows, OS/2, Mac) which represent a significant share (90%?) of the
potential Ada users have this same problem. That is a good enough
reason to have some form of standard interface.

I do not say that this functionality (including Ada.Command_Line)
should be part of the standardized Ada language. Issues like these are
very well suited to less formal standardizing, like including extra
functionality in the GNAT standard libraries. These might perhaps be
separated from the Ada.* hierarchy in an Extra.* hierarchy.

Given the significant use of GNAT in proportion to other Ada-95
compilers, an initiative (supported) by the developers of GNAT in this
direction might be followed by others and become a de facto standard.

Important areas to be covered by such an extension would be:

* Terminal IO including cursor positioning commands and attribute
changes. Of course these should be stored with each Terminal_IO file
opened, so multiple tasks can maintain there own position/attributes
without interfering with other tasks using the same terminal.

* File-system support for changing current directory, querying
information about files in the current directory and 
deleting/renaming files.

* Network IO which would at least support (a subset of) populair
TCP/IP networking, so there is a common way of communicating
between computers connected to the Internet.


These are points that have very much in common on the major platforms
like Dos, Unix, OS/2, Macintosh and Windows, although not all platforms
will have standard support for all areas. 

This is no reason however to *not* make *any* attempt to standardize
on these very common external interfaces. Many programs only need
the very simple common features described above which can have good
portability between platforms. 

Is it really necessary that every Ada user invents his own
ANSI-emulator? Should everybody make his own platform-specific
procedure for deleting an external file? 
Is that what code reuse is all about?

I suggest that we, as Ada users and c.l.a. readers/writers, make
an effort to standardize on specifications for these interfaces.
Implementing them is easy enough.

Regards,
   Geert
-- 
E-Mail: geert@sun3.iaf.nl