Re: how to clean user

Tad,

There are enough ways to isolate and clean data.  A total reset
is hardly ever a good idea and pretty hard to implement because
there is a lot of state in the system.  Eventually,
SWI-Prolog is likely to get a transactional database, which can
simplify some of these scenarios.

A bigger worry for this type of dynamically swapping code however is 
that not everything is reclaimed, so you will suffer from memory leaks.
Notably modules, predicates and functors (name/arity pairs) are never 
reclaimed.  Modules can be wiped, but the module structure is not 
deleted and while the clauses of a predicate are truely removed, the
predicate structure is not.

So, somehow you have to ensure that you reuse modules and predicates
if you want to run 24*7.

	Cheers --- Jan

On 10/23/2013 01:29 PM, Tad Szuba wrote:
> Hi!
>
> Thanks! - now I will experiment with abolish/1
>
> However; I think, that function for reseting the user is necessary.
>
> I case of "intelligent agents" ; even single agent is restarting again
> and again his business planning strategy ;
>
> from scratch, because new facts are emerging and continuation of
> previous thread of inference is bad solution.
>
> With best regards
> Tad
> //////////////////////////////////
>
>
> -----Oryginalna wiadomość----- From: Jan Wielemaker
> Sent: Wednesday, October 23, 2013 1:03 PM
> To: Tad Szuba ; Paul Singleton
> Subject: Re: how to clean user
>
> On 10/23/2013 11:48 AM, Tad Szuba wrote:
>> Hi!
>>
>> My Java --> Prolog --> Java system
>>      for A. Smith Invisible Hand of Market simulations is "almost
>> working"
>>
>>    however I face problem ...
>>
>> When Prolog is used for next agent to infer for him (file
>> wantsToBuy4878293086935712258)
>>
>> Prolog "user"  remembers predicates from previous inference (file
>> wantsToBuy126437475720758049)
>>
>> see:
>> ERROR: c:/users/user/workspace/mainmodule4254950593641732242.pl:1:
>>     import/1: No permission to import
>> wantsToBuy4878293086935712258:goodsWB/5 into user (already imported from
>> wantsToBuy126437475720758049)
>>
>> Question is on how to reset/clean "user" without total restart of Prolog
>> ...
>
> I guess that the simplest option is to make sure it isn't imported into
> user in the first place.  I.e., do not export anything from your modules
> and simply call the predicate in its module.
>
> But, you can also call abolish/1 on these predicates.  Abolish on an
> imported predicate removes the import, not the predicate itself.
>
> Cheers --- Jan
>
>>
>> I have found some old (2004) discussion regarding this problem between
>> Paul and Michal Jakob from
>> FEE Czech Technical University Prague; but without clear solution.
>>
>> With best regards
>> Tad Szuba
>> Cracow, Poland
>>
>

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