When you use with statement with open function, you do not need to close the file at the end, because with would automatically close it for you. This PEP adds a new statement " with " to the Python language to make it possible to factor out standard uses of try/finally statements.
Benefits of calling open() using “with statement”When with the block ends, it will automatically close the file. So, it reduces the number of lines of code and reduces the chances of bug.
When it requires storing some data permanently for the programming purpose, then a file is used to do this task. Generally, the open() function is used in Python to open a file for reading and writing. The open() method returns an object to work with the file.
Using with means that the file will be closed as soon as you leave the block. This is beneficial because closing a file is something that can easily be forgotten and ties up resources that you no longer need.
You should always use open()
.
As the documentation states:
When opening a file, it's preferable to use open() instead of invoking this constructor directly. file is more suited to type testing (for example, writing "isinstance(f, file)").
Also, file()
has been removed since Python 3.0.
Two reasons: The python philosophy of "There ought to be one way to do it" and file
is going away.
file
is the actual type (using e.g. file('myfile.txt')
is calling its constructor). open
is a factory function that will return a file object.
In python 3.0 file
is going to move from being a built-in to being implemented by multiple classes in the io
library (somewhat similar to Java with buffered readers, etc.)
file()
is a type, like an int or a list. open()
is a function for opening files, and will return a file
object.
This is an example of when you should use open:
f = open(filename, 'r')
for line in f:
process(line)
f.close()
This is an example of when you should use file:
class LoggingFile(file):
def write(self, data):
sys.stderr.write("Wrote %d bytes\n" % len(data))
super(LoggingFile, self).write(data)
As you can see, there's a good reason for both to exist, and a clear use-case for both.
Functionally, the two are the same; open
will call file
anyway, so currently the difference is a matter of style. The Python docs recommend using open
.
When opening a file, it's preferable to use open() instead of invoking the file constructor directly.
The reason is that in future versions they is not guaranteed to be the same (open
will become a factory function, which returns objects of different types depending on the path it's opening).
Only ever use open() for opening files. file() is actually being removed in 3.0, and it's deprecated at the moment. They've had a sort of strange relationship, but file() is going now, so there's no need to worry anymore.
The following is from the Python 2.6 docs. [bracket stuff] added by me.
When opening a file, it’s preferable to use open() instead of invoking this [file()] constructor directly. file is more suited to type testing (for example, writing isinstance(f, file)
According to Mr Van Rossum, although open() is currently an alias for file() you should use open() because this might change in the future.
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