是否被修改过
可以按照指定的属性名检查.

@param string $key

@return bool
550982
public function isDirty($key = null)
    {
        return $key === null
        ? (bool) $this->dirty
        : isset($this->dirty[$key]);
    }
602663
protected function hasKey($key)
    {
        return ($this->mode == self::MODE_INDEXED && $key == '') || \array_key_exists($key, $this->params);
    }
334911
public function has($key) {
		$keys = explode('.', $key);
		$conf = empty($this->environment) ? $this->conf : $this->conf[$this->environment];
		foreach ($keys as $v) {
			if (isset($conf[$v])) {
				$conf = $conf[$v];
			} else {
				return false;
			}
		}
		return true;
	}
28435
protected function setHeaderName(string $key)
        {
            $key = strtr(strtolower($key), '_', '-');
            if (strpos($key, 'http-') === 0) {
                $key = substr($key, 5);
            }
            return $key;
        }
1179362
public function has($key)
    {
        $keys = explode('.', $key);
        $cKeys = count($keys);
        $config = $this->_arr;

        for ($i = 0; $i < $cKeys; ++$i) {
            if (is_array($config)) {
                if (array_key_exists($keys[$i], $config)) {
                    $config = $config[$keys[$i]];
                } else {
                    return false;
                }
            } else {
                return false;
            }
        }

        return true;
    }
22821
public function remove($key)
    {
        if (array_key_exists($key, $this->settings)) {
            unset($this->settings[$key]);
            return true;
        }
        return false;
    }
1229019
public static function has(string $key):bool
    {
        return self::getViewHelper()->getView()->getValue($key) !== null;
    }
239234
public function settingsKey($key)
    {
        if (is_array($this->settings) == false || isset($this->settings[$key]) == false) {
            return false;
        }

        return $this->settings[$key];
    }
673233
public function delete(string $key): bool
    {
        $this->checkConnection(__METHOD__);
        $delete = $this->engine->delete($key);
        if ($delete && $this->index) {
            $this->index->events()
                ->trigger(Indexing::EVENT_ON_DELETE)
                ->params($key)
                ->fire();
        }

        return $delete;
    }
1239417
public function has($key)
    {
        if (!$this->isEnabled()) {
            return false;
        }

        return (false !== apc_fetch($this->prefix() . $key));
    }
1340530
public function has($key)
	{
		if (count(func_get_args()) > 1)
		{
			foreach (func_get_args() as $value)
			{
				if ( ! $this->has($value)) return false;
			}

			return true;
		}

		if (is_bool($this->input($key)) || is_array($this->input($key)))
		{
			return true;
		}

		return trim((string) $this->input($key)) !== '';
	}
430857
public function delete($key)
    {
        if ($this->has($key)) {
            unset($this->values[$key]);

            return true;
        }

        return false;
    }
1355053
public function has($key)
    {
        if (!$this->isEnabled()) {
            return false;
        }

        return (false !== $this->server->get($this->prefix . $key));
    }
732119
public function has($key)
    {
        $value = $this->get($key);
        if ($value === false) {
            return false;
        }

        return true;
    }
252642
public function delete(string $key): bool
    {
        $sql =  'DELETE FROM #__' . $this->table
                . " WHERE `" . $this->keyField
                . "`='" . $this->db->addEscape($key) . "'";
        return $this->db->query($sql);
    }
69226
public function delete($key)
    {
        $fileName = $this->getFileName($key);
        return (is_file($fileName) && unlink($fileName));
    }
880129
public function delete(string $key): bool
    {
        /**
         * @var $handle \Memcache|\Memcached
         */
        $handle = $this->_handle;
        $ret = $handle->delete($key);
        Debug::setCache(static::$type, 'delete', $key, $ret);
        return $ret;
    }