subject:"Re\: \[PHP\] $this in an XML data handler ... in a class"

Re: [PHP] $this in an XML data handler ... in a class

2002-07-03 Thread Analysis Solutions


Clay:

On Wed, Jul 03, 2002 at 02:20:56AM -0700, Clay Loveless wrote:
 
 xml_set_element_handler(
 $this-xmlparser,
 array($this,_xml_start_element),
 array($this,_xml_end_element));
 xml_set_character_data_handler(
 $this-xmlparser,
 array($this,_xml_character_data));

Without getting into all of the other potential issues in your code, allow
me to quickly point out that the function name parameters to the
set_*_handler() are supposed to be strings.  The string is to be the name
of the function.  So, for example, do this:

  xml_set_character_data_handler($this-xmlparser, '_xml_character_data');

Now, I'm not guaranteeing this will cause the function to become part of 
the class, but at least the function will be properly initiated.

--Dan

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Re: [PHP] $this in an XML data handler ... in a class

2002-07-03 Thread Clay Loveless


Actually, a careful reading of the docs reveals the following at the bottom
of each xml_set_*_handler section:

Note: Instead of a function name, an array containing an object reference
and a method name can also be supplied.

-Clay


 From: Analysis  Solutions [EMAIL PROTECTED]
 Date: Wed, 3 Jul 2002 13:14:34 -0400
 To: PHP List [EMAIL PROTECTED]
 Subject: Re: [PHP] $this in an XML data handler ... in a class
 
 Clay:
 
 On Wed, Jul 03, 2002 at 02:20:56AM -0700, Clay Loveless wrote:
 
 xml_set_element_handler(
 $this-xmlparser,
 array($this,_xml_start_element),
 array($this,_xml_end_element));
 xml_set_character_data_handler(
 $this-xmlparser,
 array($this,_xml_character_data));
 
 Without getting into all of the other potential issues in your code, allow
 me to quickly point out that the function name parameters to the
 set_*_handler() are supposed to be strings.  The string is to be the name
 of the function.  So, for example, do this:
 
 xml_set_character_data_handler($this-xmlparser, '_xml_character_data');
 
 Now, I'm not guaranteeing this will cause the function to become part of
 the class, but at least the function will be properly initiated.
 
 --Dan


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Re: [PHP] $this in an XML data handler ... in a class

2002-07-03 Thread Clay Loveless


In a follow up on this, here's something else that's kind of bizzare ...

Within this class example, if I add a variable declaration of:

var $testval = 'this is a test';

And then add to _xml_character_data():

echo TEST: $this-testval\n;

... I find that within the class structure, _xml_character_data can READ the
$this-testval values (set outside of any callback function), but apparently
the _xml_start_element() callback function cannot SET
$this-current_element.

My output is:

element is:
data is: [valid data]
TEST: this is a test

Is this a bug? It's beginning to have the feel of one...

-Clay



 Here's a brain-bender ... At least it is for me at the moment. : )
 
 When I use an XML parser inside a class, the xml_*_handler functions
 aren't
 recognizing $this- variables. I can kind of see why ... But would like
 it
 to work anyway. : )
 
 Here's an example:
 
 class Blah
 {
 var $xmlparser;
 var $current_element;
 
 // ...
 
 function _parseXML($data)
 {
 $this-xmlparser = xml_parser_create();
 xml_set_element_handler(
 $this-xmlparser,
 array($this,_xml_start_element),
 array($this,_xml_end_element));
 xml_set_character_data_handler(
 $this-xmlparser,
 array($this,_xml_character_data));
 xml_parse($this-xmlparser, $data);
 xml_parser_free($this-xmlparser);
 }
 
 function _xml_start_element($p, $e_name, $e_attributes)
 {
 $this-current_element = $e_name;
 }
 
 function _xml_end_element($p, $e_name)
 {
 // ...
 }
 
 function _xml_character_data($p, $data)
 {
 echo element is: .$this-current_element.\n;
 echo data is: $data\n;
 }
 
 } // end of class Blah
 
 
 
 When this XML parser gets called from within the Blah class, the element
 is: portion of _xml_character_data comes out blank!
 
 This sort of makes sense, because the callback functions are children of
 the xml_parser_create parent ... But should that make the children
 ignorant of the grandparent variables referred to by $this-varname?
 
 I hope this makes sense ... Has anyone else encountered this sort of
 problem? I'm an old hat at PHP, but am relatively new to both XML parsing
 and writing my own classes.
 
 Thanks,
 Clay
 


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Re: [PHP] $this in an XML data handler ... in a class

2002-07-03 Thread Analysis Solutions


Clay:

On Wed, Jul 03, 2002 at 11:05:34AM -0700, Clay Loveless wrote:
 
 Note: Instead of a function name, an array containing an object reference
 and a method name can also be supplied.

Interesting.  Thanks!

Anyway, back to your situation.  I put together a test.  Two counters are
running and get displayed each time each function is called.  One counter
is a regular variable which I bring into each function via a global
statement.  The other counter is part of the object.

Interestingly, in this case, the object variables are not acting as if
they are part of the class, rather they're behaving as if their scope is
stuck within each function.

As far as parsing XML, be aware that the character data handler get's
called for each bit of non-tag data, including white spaces in tags and
between tags.  And, character data can contain multiple lines but they get
passed through the character data handler function one line at a time, not
all at once.  So, performing maneuvers in the character_handler function
is tricky.  I save my character data in an array and then implode the
array in the end handler function.  This process is in the test, below, as
well.

I've got a PHP XML expat parsing tutorial up on the web that may prove 
helpful:  http://www.analysisandsolutions.com/code/phpxml.htm


#! /usr/local/bin/php -q
?php

class Blah
{
var $xmlparser;
var $current_element;
var $count = 0;

function _parseXML($data)
{
global $g;
$g = 0;

$this-xmlparser = xml_parser_create();
xml_set_element_handler(
$this-xmlparser,
array($this,_xml_start_element),
array($this,_xml_end_element));
xml_set_character_data_handler(
$this-xmlparser,
array($this,_xml_character_data));
xml_parse($this-xmlparser, $data);
xml_parser_free($this-xmlparser);
}

function _xml_start_element($p, $e_name, $e_attributes)
{
   global $CData, $g;
   $CData = array();
   echo 'g:' . ++$g . ' o:' . ++$this-count .  start\n;
   echo   start element: $e_name\n;
}

function _xml_character_data($p, $data)
{
   global $CData, $g;
   $CData[] = $data;
   echo 'g:' . ++$g . ' o:' . ++$this-count .  character\n;
   echo   character data: $data\n;
}

function _xml_end_element($p, $e_name)
{
   global $CData, $g;
   echo 'g:' . ++$g . ' o:' . ++$this-count .  end\n;
   echo   end element: $e_name\n;
   echo   end data array:  . trim( implode('', $CData) ) . \n;
}


} // end of class Blah


$XML = '
doc
 item
  Some Item Text
 /item
/doc
';

echo $XML\n;

$Class = new Blah();
$Class-_parseXML($XML);


?


Enjoy,

--Dan

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Re: [PHP] $this in an XML data handler ... in a class

2002-07-03 Thread Clay Loveless


Dan,

Thanks for your reply ... Glad to be helpful on the one tidbit I uncovered!

Looks like your conclusion is the same as mine:  the object variables are
readable within the handler functions, but they are not writeable. Hence
your use of the global variables ... That seems to be the only workaround.

I'm convinced this has to be a bug ... Because what good is a contained
class if you've got to interact with global variables in order to get the
job done? Theoretically speaking, how do you know that you're not stepping
on the toes of some other global variable?

This solution may be good enough for me and you ... If we're not writing
classes for distribution ... But they go against the grain of all the
bennies I've read about classes.

I'm not normally one to cry 'BUG!' ... But I think this qualifies. Do you
agree?

-Clay


 From: Analysis  Solutions [EMAIL PROTECTED]
 Date: Wed, 3 Jul 2002 16:38:38 -0400
 To: PHP List [EMAIL PROTECTED]
 Subject: Re: [PHP] $this in an XML data handler ... in a class
 
 Clay:
 
 On Wed, Jul 03, 2002 at 11:05:34AM -0700, Clay Loveless wrote:
 
 Note: Instead of a function name, an array containing an object reference
 and a method name can also be supplied.
 
 Interesting.  Thanks!
 
 Anyway, back to your situation.  I put together a test.  Two counters are
 running and get displayed each time each function is called.  One counter
 is a regular variable which I bring into each function via a global
 statement.  The other counter is part of the object.
 
 Interestingly, in this case, the object variables are not acting as if
 they are part of the class, rather they're behaving as if their scope is
 stuck within each function.
 
 As far as parsing XML, be aware that the character data handler get's
 called for each bit of non-tag data, including white spaces in tags and
 between tags.  And, character data can contain multiple lines but they get
 passed through the character data handler function one line at a time, not
 all at once.  So, performing maneuvers in the character_handler function
 is tricky.  I save my character data in an array and then implode the
 array in the end handler function.  This process is in the test, below, as
 well.
 
 I've got a PHP XML expat parsing tutorial up on the web that may prove
 helpful:  http://www.analysisandsolutions.com/code/phpxml.htm
 
 
 #! /usr/local/bin/php -q
 ?php
 
 class Blah
 {
   var $xmlparser;
   var $current_element;
   var $count = 0;
 
   function _parseXML($data)
   {
   global $g;
   $g = 0;
 
   $this-xmlparser = xml_parser_create();
   xml_set_element_handler(
   $this-xmlparser,
   array($this,_xml_start_element),
   array($this,_xml_end_element));
   xml_set_character_data_handler(
   $this-xmlparser,
   array($this,_xml_character_data));
   xml_parse($this-xmlparser, $data);
   xml_parser_free($this-xmlparser);
   }
 
   function _xml_start_element($p, $e_name, $e_attributes)
   {
  global $CData, $g;
  $CData = array();
  echo 'g:' . ++$g . ' o:' . ++$this-count .  start\n;
  echo   start element: $e_name\n;
   }
 
   function _xml_character_data($p, $data)
   {
  global $CData, $g;
  $CData[] = $data;
  echo 'g:' . ++$g . ' o:' . ++$this-count .  character\n;
  echo   character data: $data\n;
   }
 
   function _xml_end_element($p, $e_name)
   {
  global $CData, $g;
  echo 'g:' . ++$g . ' o:' . ++$this-count .  end\n;
  echo   end element: $e_name\n;
  echo   end data array:  . trim( implode('', $CData) ) . \n;
   }
 
 
 } // end of class Blah
 
 
 $XML = '
 doc
 item
 Some Item Text
 /item
 /doc
 ';
 
 echo $XML\n;
 
 $Class = new Blah();
 $Class-_parseXML($XML);
 
 
 ?
 
 
 Enjoy,
 
 --Dan
 
 -- 
  PHP classes that make web design easier
   SQL Solution  |   Layout Solution   |  Form Solution
   sqlsolution.info  | layoutsolution.info |  formsolution.info
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Re: [PHP] $this in an XML data handler ... in a class

2002-07-03 Thread Analysis Solutions


Hey Clay:

On Wed, Jul 03, 2002 at 03:25:42PM -0700, Clay Loveless wrote:
 
 Looks like your conclusion is the same as mine:  the object variables are
 readable within the handler functions, but they are not writeable.

I don't think that's an accurate description.  The object variables are 
writiable, but their scope remains within the particular funciton.  So, in 
essence, in my test, there are three $this-count variables floating 
around -- one for each function.


 I'm convinced this has to be a bug ... Because what good is a contained
 class if you've got to interact with global variables in order to get the
 job done?

Well, it may or may not be a bug.  This strange behavior is probably due 
to the special nature of the XML functions.  They don't really seem to be 
integrated into the class.

Other user defined methods inside classes still behave as usual.  With 
the scope of object variables being global to the object and all methods 
therein.

Further clarification on this subject need to be provided by someone with 
a better understanding PHP's inner workings.

--Dan

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Re: [PHP] $this in an XML data handler ... in a class

Re: [PHP] $this in an XML data handler ... in a class

Re: [PHP] $this in an XML data handler ... in a class

Re: [PHP] $this in an XML data handler ... in a class

Re: [PHP] $this in an XML data handler ... in a class

Re: [PHP] $this in an XML data handler ... in a class

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