RE: [PHP-DB] Calling functions recursively: recursive PHP functions
Thanks John. Your comment helped me through. I used a static variable
for the array, array_merge_recursive() function to accumulate the
foreign keys and $this->kgforeignkeys as a recursive function in a loop.
This all works ok!
function kgforeignkeys($tablename = "" )
{
static $totalkgArr;
if ( $this->connection && $tablename != "" )
{
$keylist = "";
$sql = "SELECT conname,
pg_catalog.pg_get_constraintdef(oid) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = (SELECT c.oid
FROM pg_catalog.pg_class c
LEFT JOIN pg_catalog.pg_namespace
n
ON n.oid = c.relnamespace
WHERE
pg_catalog.pg_table_is_visible(c.oid)
AND c.relname ~ '^" .
$tablename . "$' )
AND r.contype = 'f'";
$keylist = pg_query ($this->connection, $sql);
$num_rows = pg_num_rows($keylist);
for ($i=0; $i < $num_rows; $i++)
{
$r = pg_fetch_row($keylist);
// echo "Field: $r[0], $r[1] ";
$phrase = split("\(|\)", $r[1]);
// echo "Phrase: $phrase[0], $phrase[1], $phrase[2],
$phrase[3],
$phrase[4] ";
$kgArr[$i][0][0] = $tablename;
$word1 = split(",", $phrase[1]);
for ($j=1; $j <= count($word1); $j++)
{
$kgArr[$i][0][$j] = trim($word1[$j - 1]);
}
$kgArr[$i][1][0] = trim(Substr($phrase[2],
strrpos($phrase[2], "
")));
$word2 = split(",", $phrase[3]);
for ($j=1; $j <= count($word2); $j++)
{
$kgArr[$i][1][$j] = trim($word2[$j - 1]);
}
}
pg_free_result ($keylist);
$totalkgArr = array_merge_recursive($totalkgArr, $kgArr );
for ($h=0; $h < $num_rows; $h++)
{
$totalkgArr = $this->kgforeignkeys( $kgArr[$h][1][0] );
}
return $totalkgArr;
}
else
{
echo 'Failed to obtain the foreign keys in ' . $tablename .
'';
return $totalkgArr;
}
}
On Mon, 2003-01-27 at 19:57, John W. Holmes wrote:
> [snip]
> > > function Test()
> > {
> > static $count = 0;
> >
> > $count++;
> > echo $count;
> > if ($count < 10) {
> > Test ();
> > }
> > $count--;
> > }
> > ?>
> >
>
> **
> > *
> > Interesting but I am still lost as I need some help with
> > methods/functions within objects:
> > In the above example do I need to access Test() by:
> >
> > if ($count < 10) {
> > this->Test ();
>
> Yes, without the space: $this->Test();
>
> ---John W. Holmes...
>
> PHP Architect - A monthly magazine for PHP Professionals. Get your copy
> today. http://www.phparch.com/
>
>
>
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Re: [PHP-DB] Calling functions recursively
There are some cases where I see recursive functions as the only
option. Picture this function to retrieve data from a global array:
$data =
array(array('somedata'=>'somevalue','somedata2'=>'somevalue2'),array('somedata'=>'somevalue','somedata2'=>'somevalue2'),array('somedata'=>'somevalue','somedata2'=>'somevalue2'));
function getdata($key){
return $GLOBALS['data'][$key];
}
But what if some entries in the array should be aliases of others?
Using a recursive function, it's simple:
$data =
array(array('somedata'=>'somevalue','somedata2'=>'somevalue2'),'ALIAS0',array('somedata'=>'somevalue','somedata2'=>'somevalue2'),array('somedata'=>'somevalue','somedata2'=>'somevalue2'));
function getdata($key){
if(!is_array($GLOBALS['data'][$key])){
preg_match('/^ALIAS([0-9]+)$/',$GLOBALS['data'][$key],$matches);
return getdata($matches[1]);
}else{
return $GLOBALS['data'][$key];
}
}
The array could be fetched inside of the if block, but that would make
for longer code, harder to change code, and aliases of aliases would be
impossible to have.
Roberto Plomp wrote:
If you mean that it would be more straight forward, hence neater and more
comprehensive and more maintenance and stack friendly to just call the
function in a loop, I agree.
On the other hand ... well, there are arguments for the recursive approach
for a number of algorithms.
Personally I prefer not to use recursive functions, have never really seen
the absolute necessity to do so.
Roberto
- Original Message -
From: "Jason Wong" <[EMAIL PROTECTED]>
Subject: Re: [PHP-DB] Calling functions recursively
On Saturday 25 January 2003 14:49, Kevin Gordon wrote:
Can functions / methods be called recursively? If so how can this be
done? Comments much appreciated.
google > "php recursive functions"
--
Jason Wong -> Gremlins Associates -> www.gremlins.biz
Open Source Software Systems Integrators
* Web Design & Hosting * Internet & Intranet Applications Development *
/*
QOTD:
"I've just learned about his illness. Let's hope it's nothing
trivial."
*/
--
The above message is encrypted with double rot13 encoding. Any unauthorized attempt to decrypt it will be prosecuted to the full extent of the law.
RE: [PHP-DB] Calling functions recursively: recursive PHP functions
[snip]
> function Test()
> {
> static $count = 0;
>
> $count++;
> echo $count;
> if ($count < 10) {
> Test ();
> }
> $count--;
> }
> ?>
>
**
> *
> Interesting but I am still lost as I need some help with
> methods/functions within objects:
> In the above example do I need to access Test() by:
>
> if ($count < 10) {
> this->Test ();
Yes, without the space: $this->Test();
---John W. Holmes...
PHP Architect - A monthly magazine for PHP Professionals. Get your copy
today. http://www.phparch.com/
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Re: [PHP-DB] Calling functions recursively: recursive PHP functions
Roberto & Jason thank you for your comments.
Please note the question at the end of this email.
I searched on "recursive PHP functions" and found:
[thelist] recursive PHP functions
Rob Wilson thelist at lists.evolt.org
Mon Sep 16 11:00:01 2002
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That should read
10)
{
return $n;
}
echo "N =" . $n . "";
$n++;
return recursive ($n);
}
echo "The result:".recursive(1)."";
?>
With the important line being the :
return recursive ( $n );
This allows you to unwind the recursion correctly.
HTH
Rob
*
Under www.zend.com/manual chapter 8 "Variable scope" a mention of
recursion:
Static variables also provide one way to deal with recursive functions.
A recursive function is one which calls itself. Care must be taken when
writing a recursive function because it is possible to make it recurse
indefinitely. You must make sure you have an adequate way of terminating
the recursion. The following simple function recursively counts to 10,
using the static variable $count to know when to stop:
***
Interesting but I am still lost as I need some help with
methods/functions within objects:
In the above example do I need to access Test() by:
if ($count < 10) {
this->Test ();
Comments please.
Kevin Gordon
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Re: [PHP-DB] Calling functions recursively
If you mean that it would be more straight forward, hence neater and more comprehensive and more maintenance and stack friendly to just call the function in a loop, I agree. On the other hand ... well, there are arguments for the recursive approach for a number of algorithms. Personally I prefer not to use recursive functions, have never really seen the absolute necessity to do so. Roberto - Original Message - From: "Jason Wong" <[EMAIL PROTECTED]> Subject: Re: [PHP-DB] Calling functions recursively > On Saturday 25 January 2003 14:49, Kevin Gordon wrote: > > Can functions / methods be called recursively? If so how can this be > > done? Comments much appreciated. > > google > "php recursive functions" > > -- > Jason Wong -> Gremlins Associates -> www.gremlins.biz > Open Source Software Systems Integrators > * Web Design & Hosting * Internet & Intranet Applications Development * > > > /* > QOTD: > "I've just learned about his illness. Let's hope it's nothing > trivial." > */ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] Calling functions recursively
On Saturday 25 January 2003 14:49, Kevin Gordon wrote: > Can functions / methods be called recursively? If so how can this be > done? Comments much appreciated. google > "php recursive functions" -- Jason Wong -> Gremlins Associates -> www.gremlins.biz Open Source Software Systems Integrators * Web Design & Hosting * Internet & Intranet Applications Development * /* QOTD: "I've just learned about his illness. Let's hope it's nothing trivial." */ -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DB] Calling functions recursively
Kevin, Have fun and be sure to guarantee the prevent never ending looping. Roberto Counting to ten: $aCounter\n"; $aCounter++; RecursiveFunction($aCounter); } } ?> - Original Message - From: "Kevin Gordon" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, January 25, 2003 7:49 AM Subject: [PHP-DB] Calling functions recursively > Can functions / methods be called recursively? If so how can this be > done? Comments much appreciated. > Kevin Gordon > > > > > -- > PHP Database Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
