[ On 15 Jan 96, I responded to a message in which RICHARD GLIDDEN
  expressed frustration with OS/2 programming because of the VIO
  calls specifically ]

RG|... say anything useful about doing meaningful text-mode
  |applications (ie: anything that uses VIO, I still can't find
  |information on).

TD|If your using C, there is probably some help for text mode
  |available in the standard libraries.

[to which JONATHAN DE BOYNE POLLARD replied]

JDBP| For portability across compilers, the VIO subsystem is the *BEST*

[ While this did not seem to address the original problem that the
  BEGINNERS (note the subject line) were having, his point was that
  using VIO calls is not compiler dependent whereas standard library
  functions often are. To which I replied ]

TD| Additionally, I don't know of many beginner programmers who use
  | multiple compilers (especially those who don't have lots of
  | money). So portability across compilers would not seem to be an
  | important issue in this case.

[and Mr. de Boyne Pollard reiterated]

JdBP| It is if they expect to use textbooks or to ask questions here
    | in OS2PROG.
    |
    | The reason is that VIO is compiler-independent, and works the
    | same for *everyone*, both textbook writers and OS2PROG
    | participants alike.

JdBP| Not all libraries implement areas such as  in the
    | same way, and the programmer who uses  rather than
    | using the system API is asking to be both confused and
    | frustrated at the end of the day.

[To which I reply today]
First the blade, then the ear, then the full grain in the ear.

For a beginner who is frustrated with programming because there does
not seem to be enough useful information on VIO, it does not make
sense for us to insist that he use VIO because it is more consistent
across compilers. Every compiler I own came with a reference manual
and/or an online reference which describe the workings of its
included libraries. Once a programmer gets up to speed with the
concepts of the language she is using, then she is ready to dive
into operating system specifics. (And when she gets to this point, I
would recommend foregoing the VIO calls and jumping right into the
GPI.)

Additionally, every compiler has certain calling convention keywords
which are not standard. These include thunking keywords like
Borland's "__far16 pascal" and IBM's "_Far16 _Pascal"
and "_Seg16".
These are generally wrapped up in OS/2 macros like APIENTRY16.
However, sometimes it is important for the programmer to know this
and understand what these things do. It would make a great deal of
sense for someone to have a good understanding of the language
before she begins to grapple with this. And the problem is that
_when_ a programmer begins to grapple with this is seldom a personal
decision, but rather an unfortunate necessity.

And it is because of the compiler specific keywords that the source
for VIO calls is not the same from compiler to compiler. Although it
is also true that the source does appear to be the same because few
programers read the standard OS/2 include files. This is why the
OS/2 standard include files are included with each compiler and must
be ammended before using with a different compiler.

Using  is not frustrating for someone who takes the time to
read the documentation. This would no doubt be true for someone
using VIO calls too, except that for Mr. Glidden, there was not
sufficient documentation. So for him  and  would
make sense.
___
 X SLMR 2.1a X 

--- Maximus/2 2.02