Retrieving random lines from a file

A little class to retrieve a random line from a file.

import linecache, random

This class will retrieve a random line from a file.

class RandomRetriever:
"""Retrieve a random line from a file.
It caches the file, so it runs fast when used again"""
def __init__(self, fileName=None):
self.fileName = fileName
self.lineCount = self.countLine()

def countLine(self):
lines = 0
fileLines = open(self.fileName, 'r')
except IOError:
print "Cannot open "+self.fileName+" for reading"
for line in fileLines:
lines += 1
return lines

"""Retrieves a random item from the file in this class.

return A random line from the text file.
def randomItem(self):
lineNumber = random.randint(1,self.lineCount)
return linecache.getline(self.fileName, lineNumber).rstrip()