Re: strange problem with use_module

Hi Jan,


Le 03/03/2014 16:49, Jan Wielemaker a écrit :
> Dominique,
>
> It does not reproduce for me. That might be because there are some
> possibly relevant changes in the latest version. I did apply a small
> patch to avoid the trace on '$expand_goal'/2 and '$expand_term'/4.

on two of my computers there is the same behaviour
with the swi version 7.1.9.

>
> Unless you want to debug expansion logic, I suppose you do not want to
> step into use_module/1, so you use 'skip'.

Yes, if I use skip there is no error : the goal use_module(....)
succeeds.


  > The overall idea of Prolog
> debugging is to use 's' (skip) as much as possible.  If you see the
> wrong answer (often a failure), use 'r' (retry), step into (space)
> and start skipping again until you see where it goes wrong.

That is the way I use the debugger.

But in this case I was surprised by the fact that
use_module(my_module) succeeded displaying
a message (a path).
So I use the step by step graphical debugger to
see why, and the goal use_module(my_module) failed.
I was very suprised.

Anyway this is not a problem.

Thanks a lot for your answer.

Cheers,

Dominique

I was


>
>      Cheers --- Jan
>
> On 03/03/2014 02:52 PM, db wrote:
>> Hello Yan,
>>
>> Sorry for the lack of details, so here is a
>> very simple example which run
>> under Swi-prolog 64 bits, Version 6.6.1
>> (on ubuntu 12.04)
>> (the same problem appears with swi 7)
>>
>>
>> Consider 3 swi-prolog program,
>> test_module.pl, module1.pl and module2.pl
>> with :
>>
>>
>> test_module.pl
>> =====================================
>>    my_goal :-
>>       gtrace,
>>       use_module('module1.pl').
>> =====================================
>>
>> module1.pl
>> ====================================
>>    :- module(module1, []).
>>
>>    :- use_module('module2.pl').
>> ====================================
>>
>> module2.pl
>> ====================================
>>    :- module(module2, []).
>> ====================================
>>
>>
>> Now if you consult test_module.pl
>> and execute :
>> ?- my_goal.
>>
>> this lauches the graphical debugger.
>> If you use the right arrow (->) to enter in the goal
>> use_module('module1.pl'), you obtain :
>>
>> system:'$expand_term'(A, B, C, D) :-
>>      expand_term(A, B, C, D).
>>
>> with :
>>
>> A    = :-module(module1, [])
>> B    = term_position(0, 22, 0, 2, [term_position(3, 22, 3, 9, [10-17,
>> 19-21])])
>>
>> When you continue to click on the right arrow (->)
>> this finally fails with the error message :
>>
>> ERROR: Domain error: `module_file' expected, found
>> `/home/dominique/Bureau/Lea1_work/module1.pl'
>>
>> BUT :
>> If you restart from scratch (quit prolog, consult and execute my_goal).
>>
>> You again obtain the window of the graphical debugger.
>> if you use the arrow SKIP OVER (the third one from the left),
>> the goal succeeds.
>>
>> Why ?
>>
>> Thanks a lot if you have any explanation.
>>
>> Cheers.
>>
>> Dominique
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Le 03/03/2014 09:14, Jan Wielemaker a �crit :
>>
>>> You make us guess what you are doing.  From `go into',
>>> I have the impression that you use use_module/1 as a
>>> normal goal inside a program to load code dynamically,
>>> right?
>>>
>>> I could imagine that this might lead to some mixup in the
>>> source handling, but a simple test shows everything works
>>> just fine.
>>>
>>> For short, as usual we need a complete example and instructions
>>> how to make it fail ...
>>>
>>> As a work-around, it might be wise to use 's' (skip) on the
>>> use_module/1 call.  Except for the execution of some hooks,
>>> nothing should be visible anyway and there is surely nothing
>>> you can debug with the gui tracer.
>>>
>>>     Cheers --- Jan
>>>
>>>>
>>>> Dominique
>>>>
>>>>
>>>> Le 02/03/2014 22:16, db a �crit :
>>>>> Hi Jeff,
>>>>>
>>>>> I have tried your solution but there is still
>>>>> the same problem :
>>>>>
>>>>> the instruction
>>>>> use_module(my_module) (without the extension .pl)
>>>>> works without the graphical debugger
>>>>> and does not work with it.
>>>>>
>>>>> Thanks for your answer.
>>>>>
>>>>> Regards
>>>>> Dominique
>>>>>
>>>>>
>>>>> Le 02/03/2014 19:48, Jeff Rosenwald a �crit :
>>>>>> Hi Dominique:
>>>>>>
>>>>>> It doesn't work at all on the Linux distro of SWIPL.
>>>>>>
>>>>>> Please try: "use_module(my_module)." That is, omit the extension
>>>>>> and see
>>>>>> if that changes the symptom.
>>>>>>
>>>>>> Regards,
>>>>>> Jeff R.
>>>>>>
>>>>>>
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: db <[email protected]>
>>>>>> To: swi-prolog <[email protected]>
>>>>>> Sent: Sun, Mar 2, 2014 12:01 pm
>>>>>> Subject: [SWIPL] strange problem with use_module
>>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> I use SWI-Prolog (Multi-threaded, 64 bits, Version 7.1.9)
>>>>>> on Ubuntu 12.04.
>>>>>>
>>>>>> In a program I have the instruction :
>>>>>>
>>>>>> use_module('my_module.pl').
>>>>>>
>>>>>> It works if I do not use the graphical debugger.
>>>>>>
>>>>>> But when I use the graphical debugger (with gtrace),
>>>>>> I obtain the following error :
>>>>>>
>>>>>> ERROR: /home/Dominique/create_int_examples.pl:49: Initialization goal
>>>>>> raised exception:
>>>>>> ERROR: Domain error: `module_file' expected, found
>>>>>> `/home/dominique/Documents/Recherche/completion2.pl'
>>>>>>
>>>>>> Anyone would have an explanation ?
>>>>>>
>>>>>> Thanks a lot
>>>>>>
>>>>>> Dominique
>>>>>>
>>>>>>
>>>>>>
>>>>>>
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>>>>>>
>>>>>>
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