PHP “__toString” magic method: not so magic before 5.2.0
I was confident that using one of php5’s magic methods, __toString() would just work, but the fact is that the following code works in php version 5.2.1 but not in 5.1.6:
You can try this for yourself:
class ToStringTest {
protected $content;
public function __construct($content) {
$this->content = $content;
}
public function add($content) {
$this->content .= ‘ ‘ . $content;
}
public function __toString() {
return $this->content;
}
}
$A = new ToStringTest(‘Hello World (A)’);
$B = new ToStringTest(‘Hello World (B)’);
$A->add(‘!’);
$B->add( $A );
Outputs:
Hello World Hello World !
In php 5.2.1
and
Hello World Object id #1
In php 5.1.6
And then it hit me:
It is worth noting that before PHP 5.2.0 the __toString method was only called when it was directly combined with echo() or print().
Small piece of advise: always be sure to know what is a certain function’s behavior in the possible php versions your code will be running, or risk bad surprises.
Meanwhile… use
June 13th, 2007 at 12:01 pm
Nice one!
Normally I try to avoid magic functions (because I don’t believe in magic), but I thought the __toString() would be useful. I was having the same problem that you are describing here. (did a google search and found your blog).
Seems I need to update my php version on my home dev machine. Thanks for the info
November 4th, 2007 at 7:35 pm
I didn’t run the php file, but I think this outputs:
Hello World (A) !
Hello World (B) Hello World (A) !
November 6th, 2007 at 5:05 pm
You are right, my bad on that typo…
March 21st, 2008 at 4:20 pm
I came across this same problem. I made an image gallery with thumbnail generation and caching, and thoroughly tested it on my personal apache with PHP 5.2.3. Uploaded it to a friend’s webspace on her college’s server, then had to go visit some family for a week. I come back and find out that instead of displaying thumbnails that link to fullviews, it’s displaying object IDs linking to their respective fullviews. I replaced all instances of $obj that were in echoes or in other strings with $obj->__toString(), and everything worked perfect.
Had I read this sooner, I would’ve known I didn’t need to alter the actual echoes. Just the other strings.