Re: From extended Pascals to Ada 95 guide

[Marco van de Voort <marcov@stack.nl>]

About the Matrix type:

The subtype system, to me, looks like a cross between and attempt to
implement multidimensional openarrays, and GPC pascal's schemata types.

If I were you, I wouldn't be too sad that it doesn't 

> Marco:
 
> > I do. But to program apps, not to create academical perfect programs.
> > I also think portability issues are often severely overrated.
> 
> It depends on your needs.

Definitely. But portability demands always need extra time. Except if
you allow the applications limits  to be set by the portability
requirements.

> When you have to maintain a large commercial
> program that must run on NT for some customers, on Linux for others
> it's perfectly feasible in Ada (real case). 

That is the same processor, and NT is POSIX compliant. If you use some
IBCS format, you might even be able to use the same binary :-) (in
theory of course).

Well, I can only put the FPC compiler itself. 100000 lines, and
increasing daily. FreeBSD will be the fifth i386 OS.

> Try just to manage accurately
> file I/O in a portable way in Pascal, even details like 'what happens when
> such file is not there ?'. Not to make the hot-line explode...

First:
What does ADA in such case? The program always has to react to what
happens and doesn't happen in such cases. An non existant file (that
should exist) always triggers some special treatment. That treatment can
be as simple as halt-program, or reinitialise, but it is a condition set
by the programmer, not by the language.

Second: What pascal does in this case depends on the runtime library I
use, not on pascal. This is a critical difference, since in free
compilers with access to the compiler source, you can finally
remove/replace nearly
all the RTL. TS M2 was pretty much the Borland under the Modula2
compilers. (and even related to BP IIRC)

> Another important thing: you should have the choice between compilers, even
> when your program already has more than 100'000 lines. E.g. switch from
> a compiler firm A (which suddenly closed down, stopped development,
> begins to procude a unusable bloatware, has too expensive support or
> doesn't provide optimization or a Linux version) to firm B or C.

That happened to me. Not with a large codebase, but with a bunch of
small utils, non of which rocketscience, that kept a few BBSes running.
At a certain point people started using longfilenames, and I was stuck
with the TopSpeed RTL.

That's why I moved to a free compiler, and for private, or even medium
use, I'll never consider a commercial compiler again.

Not only because in problem cases you can fix problems yourself, but
compilerprojects are relatively large projects, and probably will last
for a decade in some form. (iow several generations of developpers)
 
> > >Ada is kind of like
> > >"Pascal++" in that the syntax is very much like Pascal's, but it cures
> > >certain ills that existed there and then added a *lot* more stuff to
> > >make the language much more powerful.
> 
> > Over standard pascal, or over Delphi?
> 
> Anyway, a lot over BP7. 

Yeah, but I dumped BP7 in 1993 for TopSpeed :-) (Modula-2)

I don't know much about ADA. I liked TopSpeed M2, but didn't like
ISO-M2, M3 or Oberon. 
 
> I would be glad to incorporate some details about Delphi in my comparison...

I think we should call it Object Pascal :-) Delphi is more the entire
project (including IDE, libraries etc)

Check the manuals or specs:
- Inprise (Borland) is quite generous with the helpfiles, and they are
downloadable from ftp.inprise.com/pub/delphi/techpubs (or something like
that)
- JEDI, the Delphi open source project, has a documentation project (and
tool), it is called Dolphin, and contains some nice texts.
- For the FPC implementation: download the reference manual from
	the FPC site (www.freepascal.org)

-- 

Marco van de Voort (Marcov@stack.nl or marco@freepascal.org)