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libphutil/src/object/Phobject.php
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Phobject.php
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<?php
/**
* Base class for libphutil objects. Enforces stricter object semantics than
* PHP.
*
* When a program attempts to write to an undeclared object property, PHP
* creates the property. However, in libphutil this is always an error (for
* example, a misspelled property name). Instead of permitting the write,
* subclasses will throw when an undeclared property is written.
*
* When a program attempts to iterate an object (for example, with `foreach`),
* PHP iterates its public members. However, in libphutil this is always an
* error (for example, iterating over the wrong variable). Instead of
* permitting the iteration, subclasses will throw when an object is iterated.
*
* (Legitimately iterable subclasses can provide a working implementation of
* Iterator instead.)
*/
abstract class Phobject implements Iterator {
public function __get($name) {
throw new DomainException(
pht(
'Attempt to read from undeclared property %s.',
get_class($this).'::'.$name));
}
public function __set($name, $value) {
throw new DomainException(
pht(
'Attempt to write to undeclared property %s.',
get_class($this).'::'.$name));
}
public function current() {
$this->throwOnAttemptedIteration();
}
public function key() {
$this->throwOnAttemptedIteration();
}
public function next() {
$this->throwOnAttemptedIteration();
}
public function rewind() {
$this->throwOnAttemptedIteration();
}
public function valid() {
$this->throwOnAttemptedIteration();
}
private function throwOnAttemptedIteration() {
throw new DomainException(
pht(
'Attempting to iterate an object (of class %s) which is not iterable.',
get_class($this)));
}
/**
* Read the value of a class constant.
*
* This is the same as just typing `self::CONSTANTNAME`, but throws a more
* useful message if the constant is not defined and allows the constant to
* be limited to a maximum length.
*
* @param string Name of the constant.
* @param int|null Maximum number of bytes permitted in the value.
* @return string Value of the constant.
*/
public function getPhobjectClassConstant($key, $byte_limit = null) {
$class = new ReflectionClass($this);
$const = $class->getConstant($key);
if ($const === false) {
throw new Exception(
pht(
'"%s" class "%s" must define a "%s" constant.',
__CLASS__,
get_class($this),
$key));
}
if ($byte_limit !== null) {
if (!is_string($const) || (strlen($const) > $byte_limit)) {
throw new Exception(
pht(
'"%s" class "%s" has an invalid "%s" property. Field constants '.
'must be strings and no more than %s bytes in length.',
__CLASS__,
get_class($this),
$key,
new PhutilNumber($byte_limit)));
}
}
return $const;
}
}
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