Python: NameError: 'self' is not defined

Question

I must be doing something stupid. I'm running this in Google App Engine:

class MainHandler(webapp.RequestHandler):

    def render(self, template_name, template_data):
        path = os.path.join(os.path.dirname(__file__), 'static/templates/%s.html' % template_name)
        self.response.out.write(template.render(path, template_data)) # error here

    def get(self):
        self.response.out.write("hi")

def main():
    application = webapp.WSGIApplication([('/', MainHandler)],
                                        debug=True)
    util.run_wsgi_app(application)


if __name__ == '__main__':
    main()

This gives an error:

Traceback (most recent call last):
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 3192, in _HandleRequest
    self._Dispatch(dispatcher, self.rfile, outfile, env_dict)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 3135, in _Dispatch
    base_env_dict=env_dict)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 516, in Dispatch
    base_env_dict=base_env_dict)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 2394, in Dispatch
    self._module_dict)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 2304, in ExecuteCGI
    reset_modules = exec_script(handler_path, cgi_path, hook)
  File "C:\Program Files\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 2200, in ExecuteOrImportScript
    exec module_code in script_module.__dict__
  File "main.py", line 22, in <module>
    class MainHandler(webapp.RequestHandler):
  File "main.py", line 38, in MainHandler
    self.writeOut(template.render(path, template_data))
NameError: name 'self' is not defined

What am I doing wrong?

Are you sure that code snippet provided corresponds to the stack trace? At least I see a difference on err-line. — nkrkv, Jun 03 '10 at 06:26

score 20 · Accepted Answer · answered Jun 03 '10 at 06:37

20

The exception is happening while the class is being defined, which means that your indentation is off. Tabs in Python are equivalent to 8 spaces, so if all the preceding lines are using tabs and your tabstop is set to 4 spaces then the indentation only looks correct.

answered Jun 03 '10 at 06:37

Ignacio Vazquez-Abrams

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8 spaces is an outrage. It should be 5. – detly Jun 03 '10 at 06:48
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@detly A tab should be 0 spaces. Then you can't see them, and thus they can't hurt, right? :-) – extraneon Jun 03 '10 at 06:58

score 3 · Answer 2 · edited May 23 '17 at 12:16

3

Just in case someone happens upon this and is looking for a solution not having to do with indentation, this is a good reference for how / when to use self.

NameError: name 'self' is not defined

edited May 23 '17 at 12:16

Community

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answered Sep 24 '13 at 21:05

nihiser

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score 1 · Answer 3 · answered Jun 05 '10 at 07:24

1

Most style guides for python, including the google style guide, recommend you use spaces instead of tabs... most text editors support this too. Helps you avoid mistakes like this.

answered Jun 05 '10 at 07:24

Sudhir Jonathan

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You might also use the `pep8` script or run Python with the `-tt` option to find such errors. – Philipp Jun 05 '10 at 08:06

Python: NameError: 'self' is not defined

3 Answers3