Merge pull request #1566 from darshanime/signal-example

[MRG+1] Include example for signal docs

docs/topics/signals.rst

@@ -16,6 +16,37 @@ deliver the arguments that the handler receives.
 You can connect to signals (or send your own) through the
 :ref:`topics-api-signals`.
 
+Here is a simple example showing how you can catch signals and perform some action:
+::
+
+    from scrapy import signals
+    from scrapy import Spider
+
+
+    class DmozSpider(Spider):
+        name = "dmoz"
+        allowed_domains = ["dmoz.org"]
+        start_urls = [
+            "http://www.dmoz.org/Computers/Programming/Languages/Python/Books/",
+            "http://www.dmoz.org/Computers/Programming/Languages/Python/Resources/",
+        ]
+
+
+        @classmethod
+        def from_crawler(cls, crawler, *args, **kwargs):
+            spider = super(DmozSpider, cls).from_crawler(crawler, *args, **kwargs)
+            crawler.signals.connect(spider.spider_closed, signal=signals.spider_closed)
+            return spider
+
+
+        def spider_closed(self, spider):
+            spider.logger.info('Spider closed: %s', spider.name)
+
+
+        def parse(self, response):
+            pass
+
+
 Deferred signal handlers
 ========================
 

scrapy/utils/misc.py

@@ -1,4 +1,4 @@
-"""Helper functions which doesn't fit anywhere else"""
+"""Helper functions which don't fit anywhere else"""
 import re
 import hashlib
 from importlib import import_module