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Practical PHP Programming is a wiki site that has been set up to provide a central area for PHP developers to contribute to learning and understanding PHP. This site was recently called Hudzilla and was a pretty good online PHP book.Practical PHP Programming was a pretty good site when it was just static pages, people were always linking to it from the php.net site in order to explain something that wasn't clear in the documentation. I think that the decision to turn it into a Wiki can only lead to it becoming a better resource.
Generating a PDF document from a web page through PHP can be problematic. It's often something that seems quite simple, but actually generating the document can be difficult and time consuming.
Reflection is used to gather more information about code during the runtime of the program. This allows code to inspect itself and to make small modifications, which is useful in a variety of situations.
PHP 8.1 comes with a few new additions to the language, and one that I have seen get the most attention is fibers. This is a feature that allows PHP code to be executed in a concurrent thread, with the ability to pause and resume that code at will.