Closing file handle with chained method

Question

In the case of a chained method when opening a file, eg.:

indata = open(from_file).read()

Is it necessary (or possible) to close the file handle opened with the open() function?

If not, is it best practice to instead do:

infile = open(from_file)
indata = infile.read()
infile.close()

Answer 1

In the case of a chained method when opening a file

This is the pitfall of chained method to open files, so the suggested solution is to use the with clause. The lifetime of an object is within the with block and the fileObj is closed automatically

with open(from_file) as fin:
    indata = fin.read()

Why it is wrong?

1. You are at the mercy of GC to close files
2. If exception happens, you may not know where the exception happened, while opening or while reading

The other code piece

infile = open(from_file)
indata = infile.read()
infile.close()

Has also its pitfall.

1. If an exception happens, the file may not be closed
2. The code might take a different route and the close statement may not be exceuted