[Bug-apl] fpc/freepascal interface

[enztec]

Hi  Jürgen,

> Regarding fpc it depends on how they have built their C/C++ interface (if 
> they did).
> The last time I used Pascal was the time when the only other programming
> language on my platform was BASIC. So I am not really up-to-date with Pascal.
> If you want to try it, then I can help with technical information that you 
> may need.

this is the fpc/c/c++ interface guide that i have used for accessing c libs 
from fpc
using c++ in fpc is a lot more complicated - i have 'working examples' from the 
following guide (hello++.pas) but that is it for c++.
ftp://ftp.freepascal.org/pub/fpc/docs-pdf/CinFreePascal.pdf

This is an example of the c interface (how i can use 'c/libc' from fpc)

this can be your first fpc program!!

// sysconf.pas
program sysconf; // see man 3 syscon
uses ctypes;
const _SC_NPROCESSORS_ONLN = 84; // _SC_NPROCESSORS_ONLN  The number of 
processors currently online (available).
function sysconf(i: cint): clong; cdecl; external 'c'; // libc unistd.h
begin
writeln(sysconf(_SC_NPROCESSORS_ONLN), ' cpus : _SC_NPROCESSORS_ONLN');
writeln;
end.

to compile
fpc -XX sysconf.pas # -XX use smart linking to get smallest executable   use 
-gl for generating debug info for gdb and use lineinfo unit

---

> The shell approach is fine as long as your programs process a small to medium
> amount of data. When the volume of data becomes huge then you have a lot of
> overhead (formatting on the shell side and tokenization and optimization on 
> the
> APL side) which can only be avoided by calling directly into the APL 
> interpreter.

so far i've had no problem using cli apl from fpc (there are actually 2 ways 
depending on if i want to 'trap' and use any apl standard output 
(aprocess.execute) or not (sysutils.executeprocess)

program fpcapl;
uses sysutils;
var l : ansistring;
begin
l := '-c "/usr/local/bin/apl --cfg"';
//l := '-c "/apl/workspaces/script.apl"'; //  script.apl file   has    #! 
/usr/local/bin/apl --script --     then apl code
sysutils.executeprocess('/bin/bash', l); // apl standard output just displayed
end.