Python Tutorial | Python Data File Handling 5

“with” statement in Python

“with” statement in Python is used in exception handling to make the code cleaner and much more readable. It simplifies the management of common resources like file streams. Observe the following code example on how the use of with statement makes code cleaner.

# file handling

# 1) without using “with” statement

file = open('file_path', 'w') 
file.write('hello world !') 
file.close() 

# 2) without using with statement

file = open('file_path', 'w') 
try: 
    file.write('hello world') 
finally: 
    file.close() 

# 3)using with statement

with open('file_path', 'w') as file: 
    file.write('hello world !') 

Notice that unlike the first two implementations, there is no need to call file.close() when using with statement. The with statement itself ensures proper acquisition and release of resources. An exception during the file.write() call in the first implementation can prevent the file from closing properly which may introduce several bugs in the code, i.e. many changes in files do not go into effect until the file is properly closed.

The second approach in the above example takes care of all the exceptions but using the with statement makes the code compact and much more readable. Thus, with statement helps avoiding bugs and leaks by ensuring that a resource is properly released when the code using the resource is completely executed. The with statement is popularly used with file streams.

Python Basic Programming Tutorial

Python Introduction     Getting started in Python Programming      Python propgramming fundamentals     Python Operators    Python If Condition     Python for loop    Python range construct      Python While loop    break and continue statements     Different looping techniques     Python List     Python String     Python Functions    Python Inbuilt Functions     Python Recursion     Using Python Library     Python Tuples     Python Dictionary     Python Sets     Python Strings     Python Exception Handling     Python Data File Handling

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