Problem appending new class to a list of classes

[yueying53]

I am new to creating a list of classes. Hence I checked out this website: http://www.daniweb.com/code/snippet390.html. However, I modified the code to check if a class with a particular has been created before.

My code works when I create the first class and append it to the list. However, subsequent creations and appending results in this error: "AttributeError : No __call__ method defined." Why is this so? Why does the program from the above link work but mine doesn't? How do I solve the problem?

Below are snippets of my code. If you require any other parts of it for further understanding, feel free to let me know.

Thanks a million!

class survey:
    def __init__(self,name,qn):
        self.name = name
        self.qn = qn
        self.ans_list=[]    #array of integers
        self.mean=''
        self.sd=''
        self.median=''
        self.mode=[]    #array of string
    def retrieve(self):
        debug = 'Survey name: ' + self.name + '\r\n'
        debug = debug + 'Qn: ' + self.qn + '\r\n'
        return debug

survey_no=0
surveylist=[]
while (1):
     if content_list[2].lower()=='create':
         name = content_list[3].lower()    #SURVEY NAME
         first_occur = content.find('"')+1
         last_occur = content.rfind('"')
         qn = content[first_occur: last_occur]    #SURVEY QUESTION
         reply_sms=''
         for survey in surveylist:
             if survey.name==name:
                 reply_sms = 'This survey already exists. '
                 print reply_sms
         if reply_sms=='':
             surveylist.append(survey(name, qn))
                 reply_sms = surveylist[survey_no].retrieve()
             survey_no = survey_no + 1
                     print reply_sms

[yueying53]

Hi guys,

There's an error in my previous post. Lines 16 to 18 should be aligned according to line 15. Sorry for the error!

Regards,
Sam

[bvdet]

I cannot test your code because it is incomplete. Try inheriting from object.

class survey(object):

Also, it may be helpful if you would post the error traceback which usually pinpoints the offending code.

Your problem may be in the for loop for survey in surveylist:. You are redefining the object reference survey.

[yueying53]

Hi bvdet,

I've attached my full code, and this is the error traceback:

Traceback (innermost last):
  File "C:\Program Files\Python\Pythonwin\pywin\framework\scriptutils.py", line 298, in RunScript
    debugger.run(codeObject, __main__.__dict__, start_stepping=0)
  File "C:\Program Files\Python\Pythonwin\pywin\debugger\__init__.py", line 60, in run
    _GetCurrentDebugger().run(cmd, globals,locals, start_stepping)
  File "C:\Program Files\Python\Pythonwin\pywin\debugger\debugger.py", line 582, in run
    _doexec(cmd, globals, locals)
  File "C:\Program Files\Python\Pythonwin\pywin\debugger\debugger.py", line 924, in _doexec
    exec cmd in globals, locals
  File "C:\Documents and Settings\Samantha Lim\Desktop\surveym.py", line 193, in ?
    surveylist.append(survey(name, qn))
AttributeError: no __call__ method defined

I'm quite new to this, so i'm not sure what you mean by "inheriting from object". I will go read up on it though. Meanwhile, if you happen to find out what exactly is wrong with my code, I will greatly appreciate some help.

Thank you so so much for all your help.

Regards,
Sam

[bvdet]

In your for loop for survey in surveylist:, you are redefining the class object survey as an instance of survey. Change the name of the class definitioin to Survey (capitalized).

class Survey(object):

Inheritance is a mechanism for creating a new class that builds on or modifies the behavior of an existing class. From Python 2.3 documentation:
"object( )

Return a new featureless object. object() is a base for all new style classes. It has the methods that are common to all instances of new style classes. New in version 2.2.
Changed in version 2.3: This function does not accept any arguments. Formerly, it accepted arguments but ignored them."

[boxfish]

Do what bvdet says; replace the line where you declare the survey class

class survey:

with

class survey(object):

so that the survey class inherits all the usual methods from the object class. Newer versions of Python will give you an error if you don't do this.

However, that is not the cause of your error. The problem is this line:

for survey in surveylist:

You are using the name of the survey class as the loop variable. Once it goes through this loop, it will think that every occurrence of the name survey means the counter variable, not the class. Call it something else, like i or eachSurvey or aSurvey or mySurvey or oneSurvey, and that should fix the error.

for oneSurvey in surveylist:

I hope this helps.

Edit:
Oops, bvdet got here first.

[bvdet]

Good post boxfish. I think yueying53 will get the message as well as a good explanation. :)

[boxfish]

Thanks, bvdet. By the way, you're getting close to 1337 posts.

[bvdet]

@boxfish
Ok, I'll take the bait. What is the significance of 1337 posts?

-BV

[boxfish]

It's cool to be 1337. Does this thread make it any clearer?