added runspider command to run spiders directly, without having to create a project

docs/faq.rst

@@ -113,3 +113,11 @@ the `Scrapy Recipes`_ page.
 .. _Community Spiders: http://dev.scrapy.org/wiki/CommunitySpiders
 .. _Scrapy Recipes: http://dev.scrapy.org/wiki/ScrapyRecipes
 
+Can I run a spider without creating a project?
+----------------------------------------------
+
+Yes. You can use the ``runspider`` command. For example, if you have a spider
+written in a ``my_spider.py`` file you can run it with::
+
+    scrapy-ctl.py runspider my_spider.py
+

scrapy/command/commands/runspider.py

@@ -0,0 +1,57 @@
+import sys
+import os
+
+from scrapy.xlib.pydispatch import dispatcher
+from scrapy.contrib.exporter import XmlItemExporter
+from scrapy.command import ScrapyCommand
+from scrapy.core.manager import scrapymanager
+from scrapy.core import signals
+
+def _import_file(filepath):
+    abspath = os.path.abspath(filepath)
+    dirname, file = os.path.split(abspath)
+    fname, fext = os.path.splitext(file)
+    if fext != '.py':
+        raise ValueError("Only Python files supported: %s" % abspath)
+    if dirname:
+        sys.path = [dirname] + sys.path
+    try:
+        module = __import__(fname, {}, {}, [''])
+    finally:
+        if dirname:
+            sys.path.pop(0)
+    return module
+
+
+class Command(ScrapyCommand):
+
+    requires_project = False
+
+    def syntax(self):
+        return "[options] <spider_file>"
+
+    def short_desc(self):
+        return "Run a spider"
+
+    def long_desc(self):
+        return "Run the spider defined in the given file. The file must be a " \
+            "Python module which defines a SPIDER variable with a instance of " \
+            "the spider to run."
+
+    def add_options(self, parser):
+        super(Command, self).add_options(parser)
+        parser.add_option("--output", dest="output", metavar="FILE",
+            help="store scraped items to FILE in XML format")
+
+    def run(self, args, opts):
+        if len(args) != 1:
+            return False
+        if opts.output:
+            file = open(opts.output, 'w+b')
+            exporter = XmlItemExporter(file)
+            dispatcher.connect(exporter.export_item, signal=signals.item_passed)
+            exporter.start_exporting()
+        module = _import_file(args[0])
+        scrapymanager.runonce(module.SPIDER)
+        if opts.output:
+            exporter.finish_exporting()