The Python Apprentice

Using file-like objects

Let's exploit this polymorphism across file-like objects by writing a function to count the number of words per line in a file and return that information as a list:

>>> def words_per_line(flo):...    return [len(line.split()) for line in flo.readlines()]

Now we'll open a regular text file containing the fragment of T.S. Eliot's masterpiece we created earlier, and pass it to our new function:

>>> with open("wasteland.txt", mode='rt', encoding='utf-8') as real_file:...     wpl = words_per_line(real_file)...>>> wpl[9, 8, 9, 9]

The actual type of real_file is:

>>> type(real_file)<class '_io.TextIOWrapper'>

But you shouldn't normally concern yourself with this specific type; is an internal Python implementation detail. You're ...