Re: [Gm2] cath exceptions raised in another module's init section

[Iztok Kobal]

Breeden, Thomas (tmb) wrote:
> Remember that by definition the init sections of imported modules are executed 
> before the init section of the modules that import them (barring circularities).
>    
I agree and I would like to point out that what Thomas wrote is valid 
when considering M2 perspective.

Yet, it is a slightly different considering the bytecode level 
perspective since BEGIN (that means intro of init body)  of importing 
module's init body executes before executing init bodies of imported 
modules. So as a matter of fact, importing module would in fact have 
already been executed when an exception appeared in the init section of 
imported module.

Here follows an example of XDS-C translation of M2 stack (C 
translation/perspective does not differ much from bytecode perspective) 
where you can clearly see that if you have risen en exception within 
e.g. EventBuffer init body (EventBuffer_BEGIN() call) this would have 
basically happened within PCVsystemDLL_BEGIN() call and of course also 
within the main() function which represented PCVsystem.MOD body. So 
catching of exception thrown within imported module's init body could 
theoretically be performed wherever up the stack while I can not see 
what M2 syntax could really do it (that is - what Martin wants) except 
within the throwing init body :-\ . I mean, if I put the M2's TRY.EXCEPT 
syntax within the PCVsystemDLL's init body it would perform only after 
all imported modules' init bodies have been executed.


MODULE PCVsystem;
IMPORT PCVsystemDLL;
BEGIN
  RETURN
END PCVsystem.

DEFINITION MODULE PCVsystemDLL;
END PCVsystemDLL.

IMPLEMENTATION MODULE PCVsystemDLL;
IMPORT ASCII;
IMPORT Critical;
IMPORT DLL;
IMPORT Error;
IMPORT EventBuffer;
BEGIN (* DllMain *)
END PCVsystemDLL.

And now C:

/* PCVsystem.MOD translation: Generated by XDS Modula-2 to ANSI C v4.20 
translator */
#define X2C_int32
#define X2C_index32
#ifndef X2C_H_
#include "X2C.h"
#endif
#define PCVsystem_C_
#ifndef PCVsystemDLL_H_
#include "PCVsystemDLL.h"
#endif
X2C_STACK_LIMIT(100000l)
extern int main(int argc, char **argv)
{
   X2C_BEGIN(&argc,argv,1,4000000l,8000000l);
   PCVsystemDLL_BEGIN();
   X2C_EXIT();
   return 0;
}
X2C_MAIN_DEFINITION

/* PCVsystemDLL.DEF translation: Generated by XDS Modula-2 to ANSI C 
v4.20 translator */
#ifndef PCVsystemDLL_H_
#define PCVsystemDLL_H_
#ifndef X2C_H_
#include "X2C.h"
#endif
extern void PCVsystemDLL_BEGIN(void);
#endif /* PCVsystemDLL_H_ */

/* PCVsystemDLL.MOD translation: Generated by XDS Modula-2 to ANSI C 
v4.20 translator */
#define X2C_int32
#define X2C_index32
#ifndef PCVsystemDLL_H_
#include "PCVsystemDLL.h"
#endif
#define PCVsystemDLL_C_
#ifndef ASCII_H_
#include "ASCII.h"
#endif
#ifndef Critical_H_
#include "Critical.h"
#endif
#ifndef SYSTEMCONSTANTS_H_
#include "SYSTEMCONSTANTS.h"
#endif
#ifndef DLL_H_
#include "DLL.h"
#endif
#ifndef Error_H_
#include "Error.h"
#endif
#ifndef EventBuffer_H_
#include "EventBuffer.h"
#endif
extern void PCVsystemDLL_BEGIN(void)
{
   static int PCVsystemDLL_init = 0;
   if (PCVsystemDLL_init) return;
   PCVsystemDLL_init = 1;
   EventBuffer_BEGIN();
   Error_BEGIN();
   DLL_BEGIN();
   Critical_BEGIN();
   ASCII_BEGIN();
/* DllMain */
}


> So the initialization of the importing module has not even started when this 
> exception occurs. I'd have to check ISO to be sure, but it seems iffy to 
> transfer control to the exception part of a section that has not even started.
>
> Tom
> address@hidden
>
>    
> > -----Original Message-----
> > From:address@hidden  [mailto:gm2-
> > address@hidden On Behalf Of Martin Kalbfuß
> > Sent: January 06, 2010 8:49 AM
> > To: GNU Modula-2
> > Subject: [Gm2] cath exceptions raised in another module's init section
> >
> > Hi again.
> >
> > I tried the following:
> >
> > I raised an exception in the initialization section of an imported
> > module. Then I tried to catch this exception in the importing main
> > module. This didn't work. Is this the way it should be? When I throw an
> > exception in any other imported function, I can catch it in the
> > importing module.
> >
> > I have the function InitSubSystem. It can fail. So I have to call it by
> > hand, to catch the exception. But the right place to put them would be
> > the initialization section of the SubSystem's module.
> >
> > Thanks,
> >
> > --
> > Martin Kalbfuß<address@hidden>
> >
> >
> >
> > _______________________________________________
> > gm2 mailing list
> > address@hidden
> > http://lists.nongnu.org/mailman/listinfo/gm2
> >      
> >
> >
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