Bind an instance of a base to a subclass - can this be done?

[Lou Pecora]

I came up with this solution for subclassing the file object and making 
some easy I/O functions (much thanks to Maric Michaud for pointing me in 
the right direction).  My goal was to make I/O of variables easy and in 
a form that I could easily visually examine the file (which I often need 
to do).  The code also keeps it very clear as to what is being read in 
or out in a single function call.

The class (inherited from file) in file ezfile.py:

# ==== File subclass from file for EZ I/O =======================

class ezfile(file):
   
   # ---- Write items to file ------------------
   #  converts items list to string first using repr fcn.
   def printline(_, ls):
      sls=repr(ls)
      _.writelines(sls)
      
   # ---- Scan line from file & return items --------------------
   #  converts scanned string to list first using eval fcn.
   def scanline(_,):
      sls=_.readline()
      return eval(sls)


An example in a Python session:

>>> from ezfile import *

#  Define some variables
>>> x=2.334
>>> i= 7
>>> str='Some stuff here'

# Open a file and output the variables to it
>>> ff=ezfile('junk','w')
>>> ff.printline([x,i,str])
>>> ff.close()

# Open the same file and read the values back in to other variables
>>> f2=ezfile('junk','r')
>>> y,j,thestr=f2.scanline()
>>> print y,j,thestr
2.334 7 Some stuff here
>>> f2.close()
>>> 

The file content looks like this:

[2.3340000000000001, 7, 'Some stuff here']

easy to see what is saved to  the file.

It works!  Thanks, again.  Comments welcome.

-- Lou Pecora  (my views are my own) REMOVE THIS to email me.