Sharing variables between modules - Gpc

4 Sep 2002


      Hi!
I've encountered some strange problem using GPC built from may 
on HPuix 11.00.
I declare public variables in module interface and then
try to use them.
The problem is that while integer variables work perfectly
all other kinds of variables (at least files and strings) 
don't work at all.
See the following small modules:
---------------mod1.pas-------------------
module mod1 interface;
export mod1 = all;
Type
    mystr = string(7);
Var
    my_str_var : mystr;
    my_int_var : integer;
end.
module mod1 implementation;
to begin do
   writeln ('Load mod1');
end.
---------------mod2.pas--------------------
module mod2 interface
export mod2 = all;
import mod1;
procedure sSet (str_arg : mystr);
function sGet : mystr;
procedure iSet (int_arg : integer);
procedure iGet : integer;
end.
module mod2 implementation;
import mod1
procedure sSet (str_arg : mystr);
begin
   writeln ('mod2 sset str_arg:',str_arg,'.');
   my_str_var := str_arg;
   writeln ('mod2 sset my_str_var:',my_str_var,'.');
end;
procedure iSet (int_arg : integer);
begin
   writeln ('mod2 sset int_arg:',int_arg,'.');
   my_int_var := int_arg;
   writeln ('mod2 sset my_int_var:',my_int_var,'.');
end;
function sGet : mystr;
begin
   sGet := my_str_var;
end;
function iGet : integer;
begin
   iGet := my_int_var;
end;
end.
-----------------------my_main.pas-------------------
program my_main (input,output);
import mod1;
import mod2;
Var
   another_str : mystr := '7654321';
   another_int : integer := 361;
begin
   sSet ('0123456');
   writeln ('1. my_main another_str:',another_str,'.');
   another_str := sGet;
   writeln ('2. my_main another_str:',another_str,'.');
iSet (19);
   writeln ('1. my_main another_int:',another_int,'.');
   another_int := iGet;
   writeln ('2. my_main another_int:',another_int,'.');
end.
--------------------------------------------------------
Well, after I compile all 3 files and run the my_main what I get is:
mod2 sset str_arg:0123456.
mod2 sset my_str_var:.
1. my_main another_str:7654321.
2. my_main another_str:.
mod2 iset int_arg:19.
mod2 iset my_int_var:19.
1. my_main another_int:361.
2. my_main another_int:19.
After I copied the my_str_var definition to implementation as well
I get the following result:
mod2 sset str_arg:0123456.
mod2 sset my_str_var:0123456.
1. my_main another_str:7654321.
2. my_main another_str:0123456.
mod2 iset int_arg:19.
mod2 iset my_int_var:19.
1. my_main another_int:361.
2. my_main another_int:19.
The strange is that after I moved my_str_var definition from
mod1 implementation to my_main var definitions nothing changed.
May somebody explain me what is going on?
Why integer is defined ok, but string has problem?
BTW as I stated earlier I have problem similar to string problem
with File variables and any structures containing string fields.
Thank you in advance.
P.S.
If the example doesn't compile - it is because of typos.
I run GPC on system which is not connected to Internet, and
the Internet computer doesn't have floppy.
P.P.S
I'd like to thank all of you who'd found out the problem with 
debuger.
Nick