python constructor basic question

I am trying to reuse an opened file which is declared inside the constructor instance of a class but I guess I am doing something logically wrong. For instance consider the following example

class Temp:
    def __init__(self):
        self.open_file_ = open('periodic_status','r')

    def function1(self):
        new_file = self.open_file_
        for i in new_file:
            print 'test1'

    def function2(self):
        for j in self.open_file_:
            print 'test2'

if __name__ == '__main__':
    obj1 = Temp()
    obj1.function1()
    obj1.function2()

In the above program I can print test1 but I am not able to print the statement test2. Can some one ex开发者_Python百科plain me the logic.

Thanks

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Because your file handle has exhausted all the lines in the file. You need to rewind it in "function2" using:

f.seek(0)

to start over again

See here docs.python.org

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Copying the reference does not create a new iterator; the first round of iteration consumes the entire file, leaving none for the second. You'll need to seek back to the beginning if you want to read it again.

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You should add open_file_.seek(0) in the beginning of function to reset the file position to the beginning (its at the end of the file after reading it all in function1()).