How to use the scrapy.conf.settings function in Scrapy

from scrapy.conf import settings
from scrapy.selector import Selector
from scrapy.http.request import Request
from scrapy_imdb.items import ImdbItem

"""
This class defines the rules according to which we extract information
from the urls we scrape. We firstly collect all the urls of the given
list and then we issue a request per url. This request results in a 
page corresponding to a movie existing in the given list. For this
movie we extract relevant information such as title, duration, etc.
"""
class ImdbSpider(Spider):
        name = "imdb"
        allowed_domains = ["imdb.com"]
        start_urls = settings['START_URLS']

        # data members
        protocol = "http"
        base_url = "www.imdb.com"

        """
        For every url existing in start_urls (each one corresponds to a
        movie list) we extract the urls of the movies in the list. 
        """
        def parse(self, response):
            sel = Selector(response)

            # xpath rule for extracting movies' urls 
            url_list = sel.xpath('//tbody[@class="lister-list"]/tr\
                    /td[@class="titleColumn"]/a/@href').extract()

def execute(argv=None, settings=None):
    if argv is None:
        argv = sys.argv

    # --- backwards compatibility for scrapy.conf.settings singleton ---
    if settings is None and 'scrapy.conf' in sys.modules:
        from scrapy import conf
        if hasattr(conf, 'settings'):
            settings = conf.settings
    # ------------------------------------------------------------------

    if settings is None:
        settings = get_project_settings()
    check_deprecated_settings(settings)

    # --- backwards compatibility for scrapy.conf.settings singleton ---
    import warnings
    from scrapy.exceptions import ScrapyDeprecationWarning
    with warnings.catch_warnings():
        warnings.simplefilter("ignore", ScrapyDeprecationWarning)
        from scrapy import conf
        conf.settings = settings
    # ------------------------------------------------------------------

    crawler = CrawlerProcess(settings)

def __init__(self):
        self.access_key = settings['AWS_ACCESS_KEY_ID']
        self.secret_key = settings['AWS_SECRET_ACCESS_KEY']

def __init__(self):
        self.mapping = settings['SOLR_MAPPING'].items()
        self.solr = pysolr.Solr(settings['SOLR_URL'], timeout=10)

def __init__(self):
        super(SimpledbStatsCollector, self).__init__()
        self._sdbdomain = settings['STATS_SDB_DOMAIN']
        self._access_key = settings['AWS_ACCESS_KEY_ID']
        self._secret_key = settings['AWS_SECRET_ACCESS_KEY']

        self._async = settings.getbool('STATS_SDB_ASYNC')
        import boto
        self.connect_sdb = boto.connect_sdb
        self.connect_sdb(aws_access_key_id=self._access_key, aws_secret_access_key=self._secret_key).create_domain(self._sdbdomain)

def update_ipaddress(self):
        '''
        Updates the scheduler so it knows its own ip address
        '''
        # assign local ip in case of exception
        self.old_ip = self.my_ip
        self.my_ip = '127.0.0.1'
        try:
            obj = urllib.request.urlopen(settings.get('PUBLIC_IP_URL',
                                  'http://ip.42.pl/raw'))
            results = self.ip_regex.findall(obj.read())
            if len(results) > 0:
                self.my_ip = results[0]
            else:
                raise IOError("Could not get valid IP Address")
            obj.close()
            self.logger.debug("Current public ip: {ip}".format(ip=self.my_ip))
        except IOError:
            self.logger.error("Could not reach out to get public ip")
            pass

        if self.old_ip != self.my_ip:
            self.logger.info("Changed Public IP: {old} -> {new}".format(
                             old=self.old_ip, new=self.my_ip))

def __init__(self):
        if not settings['ITEMSAMPLER_FILE']:
            raise NotConfigured

def __init__(self):
        if not settings.getbool('CLUSTER_WORKER_ENABLED'):
            raise NotConfigured

        self.maxproc = settings.getint('CLUSTER_WORKER_MAXPROC')
        self.logdir = settings['CLUSTER_LOGDIR']
        self.running = {} # dict of domain->ScrapyProcessControl 
        self.crawlers = {} # dict of pid->scrapy process remote pb connection
        self.starttime = datetime.datetime.utcnow()
        self.prerun_hooks = [load_object(f) for f in settings.getlist('CLUSTER_WORKER_PRERUN_HOOKS', [])]
        port = settings.getint('CLUSTER_WORKER_PORT')
        factory = pb.PBServerFactory(self, unsafeTracebacks=True)
        scrapyengine.listenTCP(port, factory)
        log.msg("Using sys.path: %s" % repr(sys.path), level=log.DEBUG)

def __init__(self):
        self.header_accept = settings.get('REQUEST_HEADER_ACCEPT')
        self.header_accept_language = settings.get('REQUEST_HEADER_ACCEPT_LANGUAGE')

def process_options(self, args, opts):
        ScrapyCommand.process_options(self, args, opts)
        if opts.nopipeline:
            settings.overrides['ITEM_PIPELINES'] = []

        if opts.nocache:
            settings.overrides['CACHE2_DIR'] = None

        if opts.restrict:
            settings.overrides['RESTRICT_TO_URLS'] = args

        if opts.nofollow:
            settings.overrides['CRAWLSPIDER_FOLLOW_LINKS'] = False