10 reasons to adopt Python 3
0 likes185 views
Python 3 provides many improvements over Python 2 including: 1) Improved comparison of different data types, iterators used more widely to reduce memory usage, and keyword-only arguments for cleaner function definitions. 2) Exceptions are now handled more cleanly with exception chaining and specific exception types for I/O errors. 3) Common library names and structures were standardized and new features were added like path handling, caching, subprocess management and async/await syntax. 4) Overall Python 3 rationalizes the language and standard library for modern use cases.
![① Comparison in Python
>>> ["user1", 20] < ["user2", 10]
True
>>> ["user1", 20] < ["user1", 30]
True](https://image.slidesharecdn.com/meetuppythontoulouse-python3-170221125918/85/10-reasons-to-adopt-Python-3-4-320.jpg)
![① Comparison in Python
Py2 : False !
Py3 : TypeError: unorderable types: tuple() < list()
>>> ("user1", 20) < ["user2", 99]
>>> max("one", 2)
"one"](https://image.slidesharecdn.com/meetuppythontoulouse-python3-170221125918/85/10-reasons-to-adopt-Python-3-5-320.jpg)
![③ Keywords Only Arguments
>>> def sortwords(
... words, reverse, case_sensitive):
>>> sortwords(
... ["one", "two", "three"],
... reverse=True, case_sensitive=False)](https://image.slidesharecdn.com/meetuppythontoulouse-python3-170221125918/85/10-reasons-to-adopt-Python-3-7-320.jpg)
![③ Keywords Only Arguments
>>> def sortwords(
... words, reverse, case_sensitive):
>>> sortwords(
... ["one", "two", "three"], True, False)
>>> def sortwords(
... words, case_sensitive, reverse):
>>> def sortwords(
... words, *, case_sensitive, reverse):](https://image.slidesharecdn.com/meetuppythontoulouse-python3-170221125918/85/10-reasons-to-adopt-Python-3-8-320.jpg)
![⑤ Chained Exceptions
Traceback (most recent call last):
File "plop.py", line 2, in <module>
connection = do_connect()
ConnectionRefusedError: [Errno 111]
Connection refused
During handling of the above exception,
another exception occurred:
Traceback (most recent call last):
File "plop.py", line 5, in <module>
connection.close()
NameError: name 'connection' is not defined](https://image.slidesharecdn.com/meetuppythontoulouse-python3-170221125918/85/10-reasons-to-adopt-Python-3-14-320.jpg)
![⑧ Stdlib Additions
>>> subprocess.run(
... ["ls", "-l"], timeout=10)
>>> datetime.now().timestamp()
>>> secrets.token_urlsafe()](https://image.slidesharecdn.com/meetuppythontoulouse-python3-170221125918/85/10-reasons-to-adopt-Python-3-20-320.jpg)
![⑨ asyncio and async/await
>>> reader,writer = await asyncio.open_connection(
... "www.python.org", 80)
... writer.write(b'GET / […]')
... async for line in reader:
... # do something with the line](https://image.slidesharecdn.com/meetuppythontoulouse-python3-170221125918/85/10-reasons-to-adopt-Python-3-22-320.jpg)
10 reasons to adopt Python 3
- 1. 10 Reasons to Adopt Python 3
- 2. About Me Pierre Fersing – pierref@bleemeo.com CTO & co-founder @Bleemeo Python & Django dev for 10 years
- 3. Monitoring as a Service solution API in Django + User Interface in ReactJS
- 4. ① Comparison in Python >>> ["user1", 20] < ["user2", 10] True >>> ["user1", 20] < ["user1", 30] True
- 5. ① Comparison in Python Py2 : False ! Py3 : TypeError: unorderable types: tuple() < list() >>> ("user1", 20) < ["user2", 99] >>> max("one", 2) "one"
- 6. ② Iterators, Iterators Everywhere Consume about 1,5 GB of memory with Python 2 ! range vs xrange, keys vs iterkeys, values vs itervalues, items vs iteritems zip, map, filter >>> for _ in range(50000000): ... the_answer = 42
- 7. ③ Keywords Only Arguments >>> def sortwords( ... words, reverse, case_sensitive): >>> sortwords( ... ["one", "two", "three"], ... reverse=True, case_sensitive=False)
- 8. ③ Keywords Only Arguments >>> def sortwords( ... words, reverse, case_sensitive): >>> sortwords( ... ["one", "two", "three"], True, False) >>> def sortwords( ... words, case_sensitive, reverse): >>> def sortwords( ... words, *, case_sensitive, reverse):
- 9. ③ Keyword Arguments >>> sortwords( ... "one", "two", "three", ... case_sensitive=False ... ) >>> def sortwords(*words, **kwargs): ... case_sensitive = ... kwargs.pop("case_sensitive")
- 10. ③ Keyword Arguments >>> sortwords( ... "one", "two", "three", ... case_sensitive=False ... ) >>> def sortwords( ... *words, case_sensitive=True):
- 11. ④ Improved Except Syntax >>> try: ... 0 / 0 ... except OSError, ZeroDivisionError: ... print("Error")
- 12. ④ Improved Except Syntax >>> try: ... 0 / 0 ... except (OSError, ZeroDivisionError) as err: ... print("Error")
- 13. ⑤ Chained Exceptions >>> try: ... connection = do_connect() ... # do stuff ... finally: ... connection.close() Traceback (most recent call last): File "code.py", line 5, in <module> connection.close() NameError: name 'connection' is not defined
- 14. ⑤ Chained Exceptions Traceback (most recent call last): File "plop.py", line 2, in <module> connection = do_connect() ConnectionRefusedError: [Errno 111] Connection refused During handling of the above exception, another exception occurred: Traceback (most recent call last): File "plop.py", line 5, in <module> connection.close() NameError: name 'connection' is not defined
- 15. ⑥ Reworked OS/IO Exception >>> try: ... fd = open("/etc/shadow") ... except IOError: ... print("Error") >>> try: ... os.stat("/etc/shadow") ... except OSError: ... print("Error")
- 16. ⑥ Reworked OS/IO Exception >>> try: ... fd = open("/etc/shadow") ... except IOError as err: ... if err.errno in (EACCES, EPERM): ... print("Error") ... else: ... raise
- 17. ⑥ Reworked OS/IO Exception >>> try: ... fd = open("/etc/shadow") ... except PermissionError: ... print("Error")
- 18. ⑦ Reworked Stdlib Names Which module ? urllib, urllib2, urlparse ? – Parsing an url : urlparse – Quoting an URL : urllib – Do a requests : urllib2 No more cPickle, cProfile, cStringIO
- 19. ⑧ Stdlib Additions >>> etc = pathlib.Path("/etc") ... file = etc / "passwd" ... file.read_text() >>> @functools.lru_cache(max_size=32) ... def expansive_function(params):
- 20. ⑧ Stdlib Additions >>> subprocess.run( ... ["ls", "-l"], timeout=10) >>> datetime.now().timestamp() >>> secrets.token_urlsafe()
- 21. ⑧ Stdlib Additions Lots more : – lzma – enum – ipaddress – faulthandler – statistics – ...
- 22. ⑨ asyncio and async/await >>> reader,writer = await asyncio.open_connection( ... "www.python.org", 80) ... writer.write(b'GET / […]') ... async for line in reader: ... # do something with the line
- 23. ⑩ Bonus >>> 1 / 2 0.5 >>> for x in iterable: ... yield x >>> yield from iterable
- 24. ⑩ Bonus Tab-completion in interpreter >>> class Children(Parent): ... def method(self): ... super().method()
- 25. ⑩ Bonus >>> round(1.5) 2 >>> round(2.5) 2
- 26. Question ?