python_advanced_01

Contents

• decorators.py: Demonstrates Python decorators, including:
  • Simple decorator with logging
  • Chaining decorators
  • Class-based decorator
  • Use of functools.wraps
• file_context_manager.py: Shows how to create a custom context manager class for file resource management using __enter__ and __exit__.
• network_context_manager.py: Demonstrates context manager usage for network connections with @contextmanager from contextlib, and exception suppression with contextlib.suppress.
• generators_iterators.py: Demonstrates Python generators, iterators, generator expressions, memory efficiency, yield from, and the itertools module.
• lock_context_manager_example.py: Demonstrates proper lock acquisition and release using context managers (threading.Lock).
• login_required_example.py: Demonstrates a simple @login_required decorator for access control.

Usage

To run the decorators example:

python decorators.py

To run the generators and iterators example:

python generators_iterators.py

To run the file context manager example:

python file_context_manager.py

To run the network context manager example:

python network_context_manager.py

To run the lock context manager example:

python lock_context_manager_example.py

To run the login required decorator example:

python login_required_example.py

Output

decorators.py

Sample output:

[LOG] Calling function: ...
[LOG] ...
Result: ...

(Shows logs for function calls, decorator chaining, class-based decorators, and @wraps effect.)

generators_iterators.py

Sample output:

Countdown:
5 4 3 2 1 0
Squares:
0 1 4 9 16
Double Countdown:
3 2 1 0 1 2 3
Large range sum (1M): 499999500000
--- itertools examples ---
itertools.count:
10 11 12 13 14 15
itertools.cycle:
A B A B A B
itertools.permutations:
(1, 2) (1, 3) (2, 1) (2, 3) (3, 1) (3, 2)
itertools.combinations:
(1, 2) (1, 3) (2, 3)

file_context_manager.py

Sample output:

[ManagedFile] Opened example.txt
[ManagedFile] Closed example.txt
[ManagedFile] Opened example.txt
[file_management_example] File content: Hello, context managers!
[ManagedFile] Closed example.txt

network_context_manager.py

Sample output (if no server is running):

[managed_socket] Connection failed: [Errno 111] Connection refused
[network_connection_example] No connection established.
[managed_socket] Socket closed
[suppress_example] FileNotFoundError suppressed.

If a server is running on localhost:5001, you will see a successful connection and data sent message.

lock_context_manager_example.py

Sample output:

Manual lock management:
[manual_lock_example] Trying to acquire lock...
[manual_lock_example] Lock acquired. Doing work...
[manual_lock_example] Lock released.

With-statement lock management:
[with_lock_example] Trying to acquire lock...
[with_lock_example] Lock acquired. Doing work...
[with_lock_example] Lock released (automatically by context manager).

login_required_example.py

Sample output:

--- Not authenticated ---
Access denied: user not authenticated.

--- Authenticated ---
User 'bob' is authenticated. Access granted.
Welcome to bob's profile!