python - Is there a need to close files that have no reference to them?

Question

As a complete beginner to programming, I am trying to understand the basic concepts of opening and closing files. One exercise I am doing is creating a script that allows me to copy the contents from one file to another.

in_file = open(from_file)
indata = in_file.read()

out_file = open(to_file, 'w')
out_file.write(indata)

out_file.close()
in_file.close()

I have tried to shorten this code and came up with this:

indata = open(from_file).read()
open(to_file, 'w').write(indata)

This works and looks a bit more efficient to me. However, this is also where I get confused. I think I left out the references to the opened files; there was no need for the in_file and out_file variables. However, does this leave me with two files that are open, but have nothing referring to them? How do I close these, or is there no need to?

Any help that sheds some light on this topic is much appreciated.

Answer 1

The pythonic way to deal with this is to use the with context manager:

with open(from_file) as in_file, open(to_file, 'w') as out_file:
    indata = in_file.read()
    out_file.write(indata)

Used with files like this, with will ensure all the necessary cleanup is done for you, even if read() or write() throw errors.