update ListProperty variable after for loop kivy

Question

I am using a for loop to cycle the months of the year and then append them to a list rather than manually type out each month.

The variable self.mylist updates mylist perfectly fine.
When for i in range(1,13): is run it updates self.mylist perfectly fine.
But because self.mylist isn't called again it doesn't update mylist after the for loop. Or so i believe is my issue.

I think this method is necessary because ListProperty cannot be appended to but can be assigned to?
So my question is after the for loop is run how can i update mylist again with self.mylist

The kv file includes only the relevant part of the problem. Which functions as intended, to grab a value from the list and display it with text:

.py file

class Telldate(AnchorLayout):
   todayday= ObjectProperty('')
   mylist=ListProperty(['','','','','','',''])

   print(mylist)

   def __init__(self,*args, **kwargs):
      super().__init__(*args, **kwargs)
      self.todayday=strftime('%A')
      self.mylist= ['this', 'does','work', 'but']
      print(self.mylist)
      for i in range(1,13):
         self.mylist.append(calendar.month_name[i])
      print(self.mylist)

class PlannerApp(App):
 #  def updater(self):
      #      Clock.schedule_interval(self.monthcyclewithglobal, 0.5)      

   def build(self):
         return Telldate()


if __name__ == '__main__':
    PlannerApp().run()

.kv file

<Telldate>:
    ---------
    -----
    --
    text:root.mylist[3]

Things I've tried but don't seem to work.
so I could define another function and use a return statement.

   def monthcycle(self):
      self.mylist= ['this', 'does','work', 'but']
      print(self.mylist)
      for i in range(1,13):
         self.mylist.append(calendar.month_name[i])
      print(self.mylist)
      return self.mylist

Or I could use global variables which doesn't seem to encouraged

   def monthcyclewithglobal():
      global mylist
      mylist= ['this', 'does','work', 'but']
      print(mylist)
      for i in range(1,13):
        mylist.append(calendar.month_name[i])
      print(mylist)
   monthcyclewithglobal() #I am aware this bit is probably terrible code

Hard coding the months in works fine. But I would like automation.
Like so

self.mylist= [ 'January', 'February', 'March', 'April', 'May', 'June', 'July', \
                     'August', 'September', 'October', 'November', 'December']

kivy V1.10.0 python V3.6.2 using IDLE V3.6.2 Thanks for your patience!

Edit1: For clarification this does not work.

   mylist=ListProperty(['','','','','','',''])
   for i in range(1,13):
     mylist.append(calendar.month_name[i])

as

AttributeError: 'kivy.properties.ListProperty' object has no attribute 'append'

Answer 1

So I solved the issue with List comprehensions.
Instead of using a loop outside the variable i want to manupilate list comprehension cut down on length of the code and made updating my variables a non issue.
I realised this while reading the docs.

class Telldate(AnchorLayout):
   mylist=ListProperty(['','','','','','','','','','','','',''])

   print(mylist)

   def __init__(self,*args, **kwargs):
      super().__init__(*args, **kwargs)
      self.mylist= [calendar.month_name[i][0:3] for i in range(1,13)]  

Hope this helps someone someday!