In Lukas Smith's latest post he looks at one of the magic methods that's built into PHP to help transform objects into strings - the __toString method. In the post he explores what it's for and what it might be used for.

The __toString() belongs to the family of methods and functions called "magic functions". They are magic because for the most part they do not get called explicitly but rather intercept operations. Unfortunately there are limits to its magic, specifically the only "context" the method is aware of is its design contract: to return a string. But its not clear what purpose that is. Should this be for some internal debugging or logging purposes? There one would be most interested in internal identifiers and object state. Is it for some frontend UI where the user will most likely be interested in some textual identifier that isn't too long as to not clutter the UI. There in lies the dilemma in the magic, while useful there is no way to ensure that the given context is passed on.

He looks at use cases for UI output (for consistent output) and contexts as well as the more internal-facing usage, like for logging and debugging purposes. Being able to get the context of the object as a string and pushed into a log at the time of error could be immensely helpful for debugging. He also links to some discussions happening on Twitter about the internal versus external uses of this magic method.

Rasmus Larsson has a recent post to his site showing how to build a basic templating engine in PHP that uses the "__toString" to help render the result.

Possibly the most common sign of bad code is tight coupling, especially between logic and presentation. It might seem like a good idea to print out the HTML while the data is being generated, but it more often than not leads to a big incoherent mess of tangled code. [...] While PHP makes it unnecessarily easy to write shitty code it also provides a lot of ways to avoid it. I’ll use this post to show you how ridiculously easy it is to create a template engine in PHP in three easy steps.

He includes the sample code for a "Template" class and shows the combination of exporting variables and output buffering to return the resulting template populated with values. The "__toString" method makes it so that you can just echo out the object and get the results.

On the Refulz.com blog there's a recent post introducing the __toString() magic method in PHP. This handy method allows you to define how to return an object when it's referenced as a string.

We started the study of PHP magic methods by learning about __get() magic method. [...] PHP is loosely typed language and same variable can be used or referred as string, number or object. The __toString() method is called when the code attempts to treat an object like a string. This function does not accept any arguments and should return a string.

Some quick code is included showing how it works - returning a combined string made from two private class properties when the object ($obj) is echoed out. They also show multiple ways of using the method in both pre- and post-PHP 5.2.

Michael Kimsal has pointed out a small irritation when using the Symfony framework and models - an issue when using models that have relationships.

If there are relations (an Author has a Book, for example). the generated forms will complain that the generated Models need a __toString() method to be used in the Form/View. In grails, this is the case, but every domain (corresponding to a Symfony 'model') has an implicit toString() method already generated, which return the string ":". For most production work, you’ll want to override it with whatever you need the string to read, but for prototyping, it's fine.

He went in and modified the Symfony core to add in a __toString call that would return the object correctly. Several of the commentors agree with his frustration and some of the Symfony developers even chime in with some of the reasoning behind why it's like that.

The Zend Developer Zone has a new post for those out there struggling with the small stuff. You've got the language down and you're learning the syntax, but there's still a few things that elude your grasp. If this is you, check out their list of "PHP Gotchas" to see if your problem is on there.

Included in their list of common problems for budding PHP developers are things like finding a "needle" in a string "haystack", working with constants, using and/or, and the __toString functionality in PHP5.

The Zend Developer Zone has a new post for those out there struggling with the small stuff. You've got the language down and you're learning the syntax, but there's still a few things that elude your grasp. If this is you, check out their list of "PHP Gotchas" to see if your problem is on there.

Included in their list of common problems for budding PHP developers are things like finding a "needle" in a string "haystack", working with constants, using and/or, and the __toString functionality in PHP5.