Defining a callback Func for preg_replace_callback(), within some class's method

[jody.florian@gmail.com]

Hi,

I'm trying to use preg_replace_ca llback within a method. The
preg_replace_ca llback() & mycallback() pair will only be used by this
method, and this method will probably only be called once in the
object's lifetime (so there's no sense in making the callback function
a method of the class...(is there??))

Instead, I wanted to use create_function () to create a make-shift
callback function within the method. (seeing as you can't define a
function within a method). However, it needs to be able to access a
property (or its getter) of the object, and it complains that it's not
within the right scope to access it.

What's the best way of doing this?

class myclass {
....
function mycallback($mat ches){
return $this->properties[$matches[1]]
}
function mymethod ($subject){
$mystr = preg_replace_ca llback(
"!{([a-z]+)}!",
array($this,'my callback'),
$subject
)
}
....
}

This above is the only way I've found of making this work so far.
However, mycallback() I really don't think should have the scope it
does, i would like its definition to stay constrained to mymethod().
any ideas would be greatly appreaciated!

Jody

[Chung Leong]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method

What you're trying to do is create a closure, which can't be done in
PHP as far as I know.

[d]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method

<jody.florian@g mail.com> wrote in message
news:1137450403 .012498.14620@g 43g2000cwa.goog legroups.com...[color=blue]
> Hi,
>
> I'm trying to use preg_replace_ca llback within a method. The
> preg_replace_ca llback() & mycallback() pair will only be used by this
> method, and this method will probably only be called once in the
> object's lifetime (so there's no sense in making the callback function
> a method of the class...(is there??))
>
> Instead, I wanted to use create_function () to create a make-shift
> callback function within the method. (seeing as you can't define a
> function within a method). However, it needs to be able to access a
> property (or its getter) of the object, and it complains that it's not
> within the right scope to access it.
>
> What's the best way of doing this?
>
> class myclass {
> ...
> function mycallback($mat ches){
> return $this->properties[$matches[1]]
> }
> function mymethod ($subject){
> $mystr = preg_replace_ca llback(
> "!{([a-z]+)}!",
> array($this,'my callback'),
> $subject
> )
> }
> ...
> }[/color]

Have you tried using the create_function property? If you read the
documentation page for preg_replace_ca llback (*ahem*), you'll see an example
:)

http://uk.php.net/manual/en/function.preg-replace-callback.php

[color=blue]
> This above is the only way I've found of making this work so far.
> However, mycallback() I really don't think should have the scope it
> does, i would like its definition to stay constrained to mymethod().
> any ideas would be greatly appreaciated!
>
> Jody
>[/color]

[jody.florian@gmail.com]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method

index.php:
<?php
class myclass {
protected $vars = array();
function addVar($name,$v al){ $this->vars[$name] = $val; }
function output(){
$fileContents = file_get_conten ts("my.template ");
$outputString = preg_replace_ca llback(
'@{([A-Z]+)}@',
create_function ('$matcharray', 'return
$this->vars[$matches[1]];'),
$fileContents);
echo $outputString;
} }
$obj = new myclass();
$obj->addVar("NAME ", "bob");
$obj->addVar("MOBILE ", "0207 PHP RULES");
$obj->addVar("EMAIL" , "bob@bob.co m");
$obj->output();
?>

my.template :
<ul>
<li>{NAME}</li>
<li>{MOBILE}</li>
<li>{EMAIL}</li>
</ul>

It produces the error:

Fatal error: Using $this when not in object context in
/www/thisproblem/index.php(10) : runtime-created function on line 1

In the example at

http://uk.php.net/manual/en/function.preg-replace-callback.php

They're not implementing a callback function with create_function () in
a class context, as opposed to my example above.

I'm still quite at a loss myself. I'm hazy on my lambda calculus but
surely there's a way round this?

--
J Florian

[jody.florian@gmail.com]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method

example.php:
<?php
class myclass {
protected $vars = array();
function addVar($name,$v al){ $this->vars[$name] = $val; }
function output(){
$fileContents = file_get_conten ts("my.template ");
$outputString = preg_replace_ca llback(
'@{([A-Z]+)}@',
create_function ('$matcharray', 'return
$this->vars[$matches[1]];'),
$fileContents);
echo $outputString;
} }

$obj = new myclass();
$obj->addVar("NAME ", "bob");
$obj->addVar("MOBILE ", "0207 PHP RULES");
$obj->addVar("EMAIL" , "b...@bob.com") ;
$obj->output();
?>

my.template :
<ul>
<li>{NAME}</li>
<li>{MOBILE}</li>
<li>{EMAIL}</li>
</ul>

It produces the error:

Fatal error: Using $this when not in object context in
/www/thisproblem/example.php(10) : runtime-created function on line 1

In the example at

http://uk.php.net/manual/en/function.preg-replace-callback.php

They're not implementing a callback function with create_function () in
a class context, as opposed to my example above.

Since it's a) not wise and b) not possible to declare a function within
a method (since it would be re-declared each time the method's used)
I'm still quite at a loss myself

I'm hazy on my lambda calculus but surely there's a way round this,
other than creating a method solely as a one-off callback?

Cheers

--
J Florian

[Chung Leong]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method

jody.florian@gm ail.com wrote:[color=blue]
>
> They're not implementing a callback function with create_function () in
> a class context, as opposed to my example above.
>
> Since it's a) not wise and b) not possible to declare a function within
> a method (since it would be re-declared each time the method's used)
> I'm still quite at a loss myself
>
> I'm hazy on my lambda calculus but surely there's a way round this,
> other than creating a method solely as a one-off callback?[/color]

Given it a rest. Like I said, PHP does not have built-in support for
closure. It's possible to implement a closure class, of course. But
then you end up with an additional class floating around instead of a
method.

If you hate having an extra method that much, just have the method call
itself and branch based on the parameter passed. Example:

function output($param = null){
if($param) {
}
else {
$outputString = preg_replace_ca llback( ... array($this,
'output') ... );
}
}

[Andy Hassall]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method

On 16 Jan 2006 17:40:31 -0800, "Chung Leong" <chernyshevsky@ hotmail.com> wrote:
[color=blue]
>What you're trying to do is create a closure, which can't be done in
>PHP as far as I know.[/color]

create_function () gets close to this.

--
Andy Hassall :: andy@andyh.co.u k :: http://www.andyh.co.uk
http://www.andyhsoftware.co.uk/space :: disk and FTP usage analysis tool

[Chung Leong]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method


Andy Hassall wrote:[color=blue]
> On 16 Jan 2006 17:40:31 -0800, "Chung Leong" <chernyshevsky@ hotmail.com> wrote:
>[color=green]
> >What you're trying to do is create a closure, which can't be done in
> >PHP as far as I know.[/color]
>
> create_function () gets close to this.
>
> --
> Andy Hassall :: andy@andyh.co.u k :: http://www.andyh.co.uk
> http://www.andyhsoftware.co.uk/space :: disk and FTP usage analysis tool[/color]

There is no good way to bind a reference to the function though, aside
from (a) a variable global (b) a wrapper class plus the array($obj,
'function') construct. PHP evidently doesn't allow lambda functions to
have static variable, so you can't give a function a private variable.

[jody.florian@gmail.com]

Re: Defining a callback Func for preg_replace_ca llback(), within some class's method

>> Given it a rest

lol. I will. I've been convinced.

Thanks for everyone's help