key; if ($key === null) return false; return array_key_exists($key, $_GET); } public function available(): bool { $key = $this->key; if ($key === null) return false; if (array_key_exists($key, $_GET)) { return $this->allowEmpty || $_GET[$key] !== ""; } else { return false; } } function get($default=null) { $key = $this->key; if ($key === null) return $default; if (array_key_exists($key, $_GET)) { $value = $_GET[$key]; if ($value === "" && !$this->allowEmpty) return $default; return $value; } else { return $default; } } function set($value): void { $key = $this->key; if ($key === null) return; cl::set($_GET, $key, $value); } function del(): void { $key = $this->key; if ($key === null) return; cl::del($_GET, $key); } }