PHPComplete has a new link this morning to an article from LaughingMeme published a while back about writing useful libraries in PHP.

It starts off talking about why the creation of good libraries for PHP is a bit more difficult than in other languages (like Perl), and notes that, since PHP is a "batteries included" language (it has a lot of the extended functionality already built in), it can be a bit more tricky to create code that can be used in more than one place. He goes on to provide a listing of 20 tips that you can use to make sure your libraries are useful not only to you, but to the general public should you decide to release the source.

Of course, this piece is one man's opinion, but it's a very well thought out and spoken one. I'd have to agree with him on several points, including "don't pollute the global namespace" and "return data/strings/objects and not HTML".