Set up start and end element handlers

# xml_set_element_handler

(PHP 4, PHP 5, PHP 7, PHP 8)

xml_set_element_handler — Set up start and end element handlers

### Description

xml_set_element_handler(XMLParser `$parser`, callable|string|null `$start_handler`, callable|string|null `$end_handler`): true

Sets the element handler functions for the XML `parser`.

`start_handler` is called when a new XML element is opened. `end_handler` is called when an XML element is closed.

### Parameters

`parser`

  The XML parser.

`start_handler`

  If `null` is passed, the handler is reset to its default state.

  Warning

  An empty string will also reset the handler, however this is deprecated as of PHP 8.4.0.

  If `handler` is a callable, the callable is set as the handler.

  If `handler` is a string, it can be the name of a method of an object set with xml_set_object().

  Warning

  This is deprecated as of PHP 8.4.0.

  Warning

  As of PHP 8.4.0, the callable is checked to be valid while setting the handler, not when it is called. This means that xml_set_object() must be called prior to setting a method string as the callback. However, as this behaviour is also deprecated as of PHP 8.4.0, using a proper callable for the method is recommended instead.

  The signature of the handler must be:

  start_element_handler(XMLParser `$parser`, string `$name`, array `$attributes`): void
  `parser`
    The XML parser calling the handler.
  `name`
    Contains the name of the element for which this handler is called. If case-folding is in effect for this parser, the element name will be in uppercase letters.
  `attributes`
    An associative array with the element's attributes. The array is empty if the element has no attributes. The keys of this array are the attribute names, the values are the attribute values. Attribute names are case-folded on the same criteria as element names. Attribute values are not case-folded. The order in which `attributes` is traversed is identical to the order in which the attributes were declared.
`end_handler`

  If `null` is passed, the handler is reset to its default state.

  Warning

  An empty string will also reset the handler, however this is deprecated as of PHP 8.4.0.

  If `handler` is a callable, the callable is set as the handler.

  If `handler` is a string, it can be the name of a method of an object set with xml_set_object().

  Warning

  This is deprecated as of PHP 8.4.0.

  Warning

  As of PHP 8.4.0, the callable is checked to be valid while setting the handler, not when it is called. This means that xml_set_object() must be called prior to setting a method string as the callback. However, as this behaviour is also deprecated as of PHP 8.4.0, using a proper callable for the method is recommended instead.

  The signature of the handler must be:

  end_element_handler(XMLParser `$parser`, string `$name`): void
  `parser`
    The XML parser calling the handler.
  `name`
    Contains the name of the element for which this handler is called. If case-folding is in effect for this parser, the element name will be in uppercase letters.

### Return Values

Always returns `true`.

### Changelog

Version | Description
--- | ---
8.4.0 | Passing a non-callable string to `handler` is now deprecated, use a proper callable for methods, or `null` to reset the handler.
8.4.0 | The validity of `handler` as a callable is now checked when setting the handler instead of checking when calling it.
8.0.0 | `parser` expects an XMLParser instance now; previously, a valid `xml` resource was expected.

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