Python basic on classes

Question

I have defined a class to process a file but get the following error when I try to instantiate the class and pass the filename. Let me know what would be the problem?

>>> class fileprocess:
... def pread(self,filename):
... print filename
... f = open(filename,'w')
... print f>>> x = fileprocess>>> x.pread('c:/test.txt')
Traceback (most recent call last):
 File "", line 1, in 
TypeError: unbound method pread() must be called with
fileprocess instance as first argument (got nothing instead)

Answer 1

x = fileprocess does not mean x is an instance of fileprocess. It means x is now an alias for the fileprocess class.

You need to create an instance, using the ().

x = fileprocess()
x.pread('c:/test.txt')

In addition, based on your original code, you could use x to create class instances.

x = fileprocess
f = x() # creates a fileprocess
f.pread('c:/test.txt')

Answer 2

x = fileprocess should be x = fileprocess()

Currently x is referring to the class itself, not an instance of the class. So when you call x.pread('c:/test.txt') that's the same as calling fileprocess.pread('c:/test.txt')

Answer 3

But why use write mode for read function? Maybe it's pwrite?