I am trying to load PHP objects stored in a database, where the class
name is stored in a column:

$object = new $resultSet->getString(1);

This fails for the same reason that the following fails:

<?php

class Foo
{
public function className()
{
return 'Foo';
}
}

$foo = new Foo;
$bar = new $foo->className();

Fatal error: Class name must be a valid object or a string in test.php
on line 12

I guess this error is due to the confusion of parsing "()" as the
argument list for the "className" function, or the "Foo" constructor...

I work around this error by using a temp variable:

$tmp = $foo->className(); $bar = new $tmp;

- however the above reads like hacky code : (

When calling dynamically named functions, I generally use
call_user_func() to avoid awkwardness with $object->$tmp($arg1, ...)

In other words, I prefer:

call_user_func(array($object, 'get'.$someName), $arg1, ...);

- to:

$tmp = 'get'.$someName; $object->$tmp($arg1, ...);

However there does not appear to be an analog of call_user_func() for
constructing new instances of dynamically named classes?

If I recall correctly, there was also a way to work around calling
dynamically named functions (e.g. $object->$tmp($arg1, ...) using
curly braces:

$object->{'get'.$someName}($arg1, ...);

- however I cannot recall the exact syntax.

Can anyone confirm that there is a curly brace syntax for calling
dynamically named functions? Could it be applied to instantiating
dynamically named classes?

Can anyone recommend a cleaner alternative to:

$tmp = $foo->className(); $bar = new $tmp;

Thanks and best wishes, Jack

On 4 May 2008, at 00:46, Jack Bates wrote:
> I am trying to load PHP objects stored in a database, where the class
> name is stored in a column:
>
> $object = new $resultSet->getString(1);
>
> This fails for the same reason that the following fails:
>
> <?php
>
> class Foo
> {
> public function className()
> {
> return 'Foo';
> }
> }
>
> $foo = new Foo;
> $bar = new $foo->className();

I would rather have a factory method that returns a new instance of
the class. There's no need for the outside world to know the class name.

<?php
class Foo
{
public function newInstance()
{
return new self();
}

public function test($a)
{
echo 'test: '.$a."\n";
}
}

$foo = new Foo;
$foo->test('foo');
$bar = $foo->newInstance();
$bar->test('bar');
?>

However, if you insist on doing it your way can I make a small
suggestion? It's better to spend your time on functionality rather
than finding ways to save some typing. I see no reason to try to
combine the two statements - saving typing and a pitiful amount of
disk space are the only benefits.

-Stut

--
http://stut.net/

On May 3, 2008, at 4:46 PM, Jack Bates <ms419@freezone.co.uk> wrote:

> I am trying to load PHP objects stored in a database, where the class
> name is stored in a column:
>
> $object = new $resultSet->getString(1);
>
> This fails for the same reason that the following fails:
>
> <?php
>
> class Foo
> {
> public function className()
> {
> return 'Foo';
> }
> }
>
> $foo = new Foo;
> $bar = new $foo->className();
>
> Fatal error: Class name must be a valid object or a string in test.php
> on line 12
>
> I guess this error is due to the confusion of parsing "()" as the
> argument list for the "className" function, or the "Foo"
> constructor...
>
> I work around this error by using a temp variable:
>
> $tmp = $foo->className(); $bar = new $tmp;
>
> - however the above reads like hacky code : (
>
> When calling dynamically named functions, I generally use
> call_user_func() to avoid awkwardness with $object->$tmp($arg1, ...)
>
> In other words, I prefer:
>
> call_user_func(array($object, 'get'.$someName), $arg1, ...);
>
> - to:
>
> $tmp = 'get'.$someName; $object->$tmp($arg1, ...);
>
> However there does not appear to be an analog of call_user_func() for
> constructing new instances of dynamically named classes?
>
> If I recall correctly, there was also a way to work around calling
> dynamically named functions (e.g. $object->$tmp($arg1, ...) using
> curly braces:
>
> $object->{'get'.$someName}($arg1, ...);
>
> - however I cannot recall the exact syntax.
>
> Can anyone confirm that there is a curly brace syntax for calling
> dynamically named functions? Could it be applied to instantiating
> dynamically named classes?
>
> Can anyone recommend a cleaner alternative to:
>
> $tmp = $foo->className(); $bar = new $tmp;
>
> Thanks and best wishes, Jack
>
Does...
<?php
$bar = new $foo->className()();
?>
....work?

Otherwise, I'd just do...
<?php
$className = $foo->className();
$bar = new $className;
?>
....instead of $tmp.
>
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