with in Python
By: Kareem in Python Tutorials on 2012-04-07
In Python, the
with statement is used to simplify the management of resources, such as file handles, network connections, or database connections, that need to be acquired and released in a certain way. The
with statement takes care of closing the resource automatically when it is no longer needed, even if an exception occurs while the resource is being used.
The basic syntax of the
with statement is:
with expression [as variable]: statement(s)
expression is a context manager object that defines the resource to be managed, and
variable is an optional variable that receives the return value of the context manager's
with statement guarantees that the
__enter__() method of the context manager is called before the block of statements, and that the
__exit__() method is called after the block of statements, even if an exception is raised. This allows the context manager to perform any setup or teardown necessary for the resource.
Here is an example that demonstrates how to use the
with statement to manage a file handle:
with open('file.txt', 'r') as f: data = f.read() print(data)
In this example, the
open() function returns a file object that is used to read data from the file. The
with statement takes care of closing the file automatically when the block of statements is finished.
You can also define your own context managers using the
contextlib module, which provides several decorators and functions for this purpose. For example, the
contextlib.closing() function can be used to create a context manager that closes a resource automatically when it is no longer needed.
This policy contains information about your privacy. By posting, you are declaring that you understand this policy:
- Your name, rating, website address, town, country, state and comment will be publicly displayed if entered.
- Aside from the data entered into these form fields, other stored data about your comment will include:
- Your IP address (not displayed)
- The time/date of your submission (displayed)
- Your email address will not be shared. It is collected for only two reasons:
- Administrative purposes, should a need to contact you arise.
- To inform you of new comments, should you subscribe to receive notifications.
- A cookie may be set on your computer. This is used to remember your inputs. It will expire by itself.
This policy is subject to change at any time and without notice.
These terms and conditions contain rules about posting comments. By submitting a comment, you are declaring that you agree with these rules:
- Although the administrator will attempt to moderate comments, it is impossible for every comment to have been moderated at any given time.
- You acknowledge that all comments express the views and opinions of the original author and not those of the administrator.
- You agree not to post any material which is knowingly false, obscene, hateful, threatening, harassing or invasive of a person's privacy.
- The administrator has the right to edit, move or remove any comment for any reason and without notice.
Failure to comply with these rules may result in being banned from submitting further comments.
These terms and conditions are subject to change at any time and without notice.
- Data Science
- React Native
- Cloud Computing
- Java Beans
- Mac OS X
- Office 365
- Tech Reviews
Python program to get location meta data from an image
Retrieve Twitter posts and comments using Python
How to install Jupyter in Ubuntu and make it accessible through Apache Reverse Proxy
Python Basics - Setting up your Python Development Environment
Schwartzian Transform in python
Multidimensional list (array) in python
Perl's chomp() equivalent for removing trailing newlines from strings in python