Rules

The following list gives an overview of which rights the PHP project reserves for itself, when choosing names for new internal identifiers. The definitive guide is the official » CODING STANDARDS:

• PHP owns the top-level namespace but tries to find decent descriptive names and avoid any obvious clashes.

• Function names use underscores between words, while class names use the camel case rule (there are some exceptions for older classes and functions).

• PHP will prefix any global symbols of an extension with the name of the extension. (In the past, there have been numerous exceptions to this rule.) Examples:

  • curl_close()

  • mysql_query()

  • PREG_SPLIT_DELIM_CAPTURE

  • new DOMDocument()

  • strpos() (example of a past mistake)

  • new SplFileObject()

• Iterators and Exceptions are however simply postfixed with "Iterator" and "Exception." Examples:

  • ArrayIterator

  • LogicException

• PHP reserves all symbols starting with __ as magical. It is recommended that you do not create symbols starting with __ in PHP unless you want to use documented magical functionality. Examples:

  • __get()

  • __autoload()