Global Namespace
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Userland Naming Guide
PHP Manual

## 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 both the camelCase and PascalCase rules.

- 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()

Global Namespace
Tips
Userland Naming Guide
PHP Manual