Help! Cannot open a file in a class

[ouj]

Hi,

I am new to Python. I write a class that opens a file and reads the
data from the file.

class Cvdoc:
    def __init__(self):
        ......
        fd = file('vdoc.dat', 'wr')
        print dir(fd)
        fd.readlines()

I used the following code to use this class:

a = Cvdoc()

And I got the following response:

$ python vdoctest.py
['__class__', '__delattr__', '__doc__', '__getattribute__', '__hash__',
'__init_ ...... ritelines', 'xreadlines']
Traceback (most recent call last):
  File "vdoctest.py", line 12, in ?
    a = Cvdoc()
  File "vdoctest.py", line 8, in __init__
    fd.readlines()
IOError: [Errno 9] Bad file descriptor

I can get access to the attributes of fd, such as fd.mode. However, I
cannot invoke the methods associated with fd, such as fd.read(), etc.

Can any one tell me help me out? Thanks a lot!

Best regards,
Jingzhao