Re: newbie prolog question, passing functions

On 26 Jul 2005 07:06:10 -0700
"mans" <mshapshak@xxxxxxxxx> wrote:

> Dear All,
>
> Very interesting material here and I would just like to sum up my
> understanding:
>
> - Everybody seems to be using a event que/dispatch model for the event
> processing to minimize the need for global variables .ie in the case of
> >>read(Event)<< from the dispatch part of the code we are accessing a global event que associated with the input buffer. Nobody seemed to confortable on calling more comlicated glocal variable structures from an direct event driven interface.
>
> - From my naive viewpoint it looks like everybody is using procedural
> conceptual model to do the coding of event driven models. Logical or
> natural language is not really used.
>

This is true of the hacks here like myself who do executeable specs and RAD prototypes.

The comp-sci academic guys tend to have more time and resources to devote to more elegant models.

> - One needs to be carefull of memory overflow and maybe event some
> garbage collection issues when doing the infinite recursive
> repeat_forever dispatch loop.
>
> Did I get some of this right?
>

Ya, I'd say it's a fairly good short-take. My own experience with Prolog
is that while it may do many neat "AI"-oriented things, it also makes a
good shovel: most of my prolog programming is _very_ plain stuff you
could do easily in C or assembly.

The fact that you can mix in bits of real declarative programming into
a procedural model makes it ideal for writing muli-language tools and
systems. As an example, here is a bit of code that provides a
general MySQL/MSSQL interface to Gprolog.

This is actually a pretty ugly bit of code, breaking a number of
programming precepts including the use of tightly-coupled co-routines,
which is exactly what this is and what makes it useful...

Dhu


/*

sqndhu.pl -- access to MSSQL and MYSQL for gprolog via php(CLI)/TDS

should work for any SQL access provided by PHP ;-)

only tested to date on a GPG/PHP/Apache/BSD box talking to MySQL on same and MSSQL on a Windos 2k box.

Duncan Patton a Campbell can be contacted at campbell@xxxxxxxxxx, or campbell@xxxxxxxx

Copyright (C) <2004> <Duncan Patton a Campbell aka Duncan Duibh>

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

*/


%MSSQL/192.168.0.22:1433/esdev2/!esdev2!/dbES_qa/
%skin_dhu(["MSSQL","192.168.0.22:1433","username","userpass","dbainstance"],["select count(*) from account_leads","select count(*) from contact_leads"],XLL).
% --> XLL = [[[[53,49,48]]],[[[53,55,49]]]]
%skin_dhu(["MYSQL","localhost:3306","username","userpass","dbainstance"],["select count(*) from urldex","select count(*) from emldex","select count(*) from rhosts"],XLL).

skin_dhu([DBTypS,HnpS,DbUnmS,DbUpsS,DbNmS],SQLstrL,XLL):-
penditaLL([DBTypS,HnpS,DbUnmS,DbUpsS,DbNmS],"/",AccS),atom_codes(AccA,AccS),
exec('/usr/local/bin/php -f /usr/local/gprolog-1.2.16/Dlib/sqndhu.php',Sin,Sout,_),
nl,write(Sin,AccA),nl(Sin),
writnread(Sin,Sout,SQLstrL,XLL),
close(Sin),close(Sout).

writnread(_,_,[],[]):-!.
writnread(Sin,Sout,[SqS|SQLstrL],[XL|XLL]):-!,
atom_codes(SqA,SqS),
nl,write(Sin,SqA),nl(Sin),
set_stream_type(Sout,binary),
readB2(Sout,[10],XYZ), %eat the first nl
readB2(Sout,[10,13],NrwS0),
str_X_lst(NrwS0,[10],[NrwS|_]),
%atom_codes(NA,NrwS),nl,write(['skin_dhu NrwS',NA]),
null_number_codes(NrwN,NrwS),
readrowS(Sout,NrwN,XL),
writnread(Sin,Sout,SQLstrL,XLL).

readrowS(_,0,[]):-!.
readrowS(Sout,NrwN,[CL|RLL]):-!,
repeat,
readB2(Sout,[10],NfldS0), %eat nl until a number comes up
str_X_lst(NfldS0,[10],[NfldS|_]),!,
null_number_codes(NfldN,NfldS),
readcolS(Sout,NfldN,CL),
NrwN_1 is NrwN - 1,
readrowS(Sout,NrwN_1,RLL).

readcolS(_,0,[]):-!.
readcolS(Sout,NfldN,[CS|CL]):-!,
readB2(Sout,[32],FlnS0),str_X_lst(FlnS0,[10,32],[FlnS|_]),
%atom_codes(FA,FlnS),nl,write(['skin_dhu FlnS',FA]),
null_number_codes(FlnN,FlnS),
readNbytes(Sout,FlnN,CS),
NfldN_1 is NfldN - 1,
readcolS(Sout,NfldN_1,CL).

readNbytes(_,0,[]):-!.
readNbytes(Sout,FlnN,[ChB|CS]):-!,
get_byte(Sout,ChB),
FlnN_1 is FlnN - 1,
readNbytes(Sout,FlnN_1,CS).

penditaLL([X],_,X):-!.
penditaLL([],_,[]):-!.
penditaLL([A|AtmLst],Sp,Catom):-!,
penditaLL(AtmLst,Sp,Catom0),!,
append(A,Sp,A1),append(A1,Catom0,Catom).

null_number_codes(0,[]):-!.
null_number_codes(N,C):- subset(C,".0123456789"),!,number_codes(N,C).
null_number_codes(_,C):-!,nl,write(['NC',C]),!,fail.


/*********************

Duncan Patton a Campbell can be contacted at campbell@xxxxxxxxxx, or campbell@xxxxxxxx

Tight coupling with sqNdhu.php -- general purpose access to SQL databases ... here implemented for commandline operations
php -f sqndhu.php
line one on stdin == MSSQL/MSHOST:1433/Uname/Upass/Dbname/
line one on stdin == MYSQL/MYHOST:3306/Uname/Upass/Dbname/
line two thru n-1 == select/insert/replace...
line n == \n

uses http://www.freetds.org/ libraries
*//*


<?php

$stdinline = trim(fgets(STDIN));

list($stype,$hnp,$dbu,$dbp,$dbn) = split("/", $stdinline) ;

switch ($stype)
{

case "MSSQL":
{
$db = mssql_connect($hnp,$dbu,$dbp);
if(!$db)
{
$handle=fopen('/tmp/perror.err', 'a');fwrite($handle, "Could not connect"); fwrite($handle, "\n\n"); fclose($handle);
exit("Could not connect");
}
if(!mssql_select_db($dbn,$db))
{
$handle=fopen('/tmp/perror.err', 'a');fwrite($handle, "Could not select database"); fwrite($handle, "\n\n"); fclose($handle);
exit("Could not select database");
}
while($squery= trim(fgets(STDIN)))
{
//$handle=fopen('/tmp/perror.err', 'a');fwrite($handle, "MySqery:".$squery); fwrite($handle, "\n\n"); fclose($handle);
$result = mssql_query($squery) or die("Query failed : " . $squery);
if(is_resource($result))
{
$num_results = mssql_num_rows($result);
echo "\n" . $num_results;
if($num_results == 0) echo "\n";
for ($i=0; $i <$num_results; $i++)
{
while($myrow = mssql_fetch_row($result))
{
$colcnt = count($myrow);
echo "\n" . $colcnt;
for($x=0; $x < $colcnt; $x++)
{
echo sprintf("\n%d ",strlen($myrow[$x])) . $myrow[$x];
}
}
}
mssql_free_result($result);
}
else
{
echo "\n1\n1\n1 !";
}
}
mssql_close($db);
}
break;

case "MYSQL":
{
$db = mysql_connect($hnp,$dbu,$dbp);
if(!$db)
{
$handle=fopen('/tmp/perror.err', 'a');fwrite($handle, "Could not connect"); fwrite($handle, "\n\n"); fclose($handle);
exit("Could not connect");
}
if(!mysql_select_db($dbn,$db))
{
$handle=fopen('/tmp/perror.err', 'a');fwrite($handle, "Could not select database"); fwrite($handle, "\n\n"); fclose($handle);
exit("Could not select database");
}
while($squery= trim(fgets(STDIN)))
{
//$handle=fopen('/tmp/perror.err', 'a');fwrite($handle, "MySqery:".$squery); fwrite($handle, "\n\n"); fclose($handle);
$result = mysql_query($squery) or die("Query failed : " . $squery);
if(is_resource($result))
{
$num_results = mysql_num_rows($result);
echo "\n" . $num_results;
if($num_results == 0) echo "\n";
for ($i=0; $i <$num_results; $i++)
{
while($myrow = mysql_fetch_row($result))
{
$colcnt = count($myrow);
echo "\n" . $colcnt;
for($x=0; $x < $colcnt; $x++)
{
echo sprintf("\n%d ",strlen($myrow[$x])) . $myrow[$x];
//$handle=fopen('/tmp/perror.err', 'a');fwrite($handle, "."); fwrite($handle, "-"); fclose($handle);
}
}
}
mysql_free_result($result);
}
else
{
echo "\n1\n1\n1 !";
}
}
mysql_close($db);
}
break;
} //end switch

fflush(STDOUT);
exit();

?>

*********************/




> Thanks Again!
> Mans
>


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