DocumentationhackLearnXHPMethods

XHP: Methods

Remember, all XHP Objects derive from the XHPRoot interface and an object that implements XHPRoot has some public methods that can be called.

XHP Object Methods

Method	Description
`appendChild(mixed $child): this`	Adds `$child` to the end of the XHP object's array of children. If `$child` is an array, each item in the array will be appended.
`categoryOf(string $cat): bool`	Returns whether the XHP object belongs to the category named `$cat`
`getAttribute(string $name): mixed`	Returns the value of the XHP object's attribute named `$name`. If the attribute is not set, `null` is returned, unless the attribute is required, in which case `XHPAttributeRequiredException` is thrown. If the attribute is not declared or does not exist, then `XHPAttributeNotSupportedException` is thrown. If the attribute you are reading is statically known, use `$this->:name` style syntax instead for better typechecker coverage.
`getAttributes(): Map<string, mixed>`	Returns the XHP object's array of attributes, as a cloned copy.
`getChildren(?string $selector = null): Vector<XHPChild>`	Returns the XHP object's children. If `$selector` is `null`, all children are returned. If `$selector` starts with `%`, all children belonging to the category named by `$selector` are returned. Otherwise, all children that are an instance of the class named by `$selector` are returned.
`getFirstChild(?string $selector = null):): ?XHPChild`	Returns the XHP object's first child. If `$selector` is `null`, the true first child is returned. Otherwise, the first child that matches `$selector` (or `null`) is returned.
`getLastChild(?string $selector = null):): ?XHPChild`	Returns the XHP object's last child. If `$selector` is `null`, the true last child is returned. Otherwise, the last child that matches `$selector` (or `null`) is returned.
`isAttributeSet(string $name): bool`	Returns whether the attribute with name `$name` is set.
`prependChild(mixed $child): this`	Adds $child to the beginning of the XHP object's array of children. If $child is an `array`, each item in the array will be appended.
`replaceChildren(...): this`	Replaces all the children of this XHP Object with the variable number of children passed to this method.
`setAttribute(string $name, mixed $val): this`	Sets the value of the XHP object's attribute named `$name`. The value will be checked against the attribute's type, and if they don't match, `XHPInvalidAttributeException` is thrown. If the attribute is not declared or does not exist, then `XHPAttributeNotSupportedException` is thrown.
`setAttributes(KeyedTraversable<string, mixed> $attrs): this`	Replaces the XHP object's array of attributes with `$attrs`. Same errors can apply as `setAttribute()`.

require __DIR__."/../../../../vendor/hh_autoload.php";

function xhp_object_methods_build_list(Vector<string> $names): XHPRoot {
  $list = <ul id="names" />;
  foreach ($names as $name) {
    $list->appendChild(<li>{$name}</li>);
  }
  return $list;
}

<<__EntryPoint>>
function xhp_object_methods_run(): void {
  $names = Vector {'Sara', 'Fred', 'Josh', 'Scott', 'Paul', 'David', 'Matthew'};
  $list = xhp_object_methods_build_list($names);
  foreach ($list->getChildren() as $child) {
    /* HH_FIXME[4067] implicit __toString() is now deprecated */
    echo <ul>{$child}</ul>."\n";
  }
  /* HH_FIXME[4067] implicit __toString() is now deprecated */
  echo <ul>{$list->getFirstChild()}</ul>."\n";
  /* HH_FIXME[4067] implicit __toString() is now deprecated */
  echo <ul>{$list->getLastChild()}</ul>."\n";
  foreach ($list->getAttributes() as $attr) {
    /* HH_FIXME[4067] implicit __toString() is now deprecated */
    echo <ul><li>{(string)$attr}</li></ul>."\n";
  }
  /* HH_FIXME[4067] implicit __toString() is now deprecated */
  echo <ul><li>{$list->getAttribute('id') as string}</li></ul>."\n";
}

Output

<ul><li>Sara</li></ul>
<ul><li>Fred</li></ul>
<ul><li>Josh</li></ul>
<ul><li>Scott</li></ul>
<ul><li>Paul</li></ul>
<ul><li>David</li></ul>
<ul><li>Matthew</li></ul>
<ul><li>Sara</li></ul>
<ul><li>Matthew</li></ul>
<ul><li>names</li></ul>
<ul><li>names</li></ul>

InterfacesXHP:

ExtendingXHP: