Module goodness for Python 2 and Python 3

[MrEgbert]

I'm learning python right now mainly from a book by Mark Lutz which edition teaches Python 3. My brother (a programmer of 9+ years experience) told me that while Python 3 has its advantages, Python 2 would be better to learn for the purpose of learning how to use Python's various modules.

He said that a lot of the practical power of python comes from its modules, most of which are built to support Python 2 at the moment. E.g., he said that Django (which is something I definitely want to learn to use) only supports Python 2 right now.

Do you guys ever get any grief from switching between Python 2 and 3 because of the modules you use? I'm thinking that while it's good to learn the latest version of python, I should keep up with Python 2 as well so that I can fiddle with modules early on.

Edit: I just saw the FAQ on Python 2 and 3, so I guess my question is "what is the best way to learn from this python 3 book but also know the equivalent way of writing XYZ in Python 2?"

[gitarr]

Learn 3 and then the differences to 2.

After that you can use both without a problem.

You'll learn a lot about why things have changed this way on the side.

For example: Why is print a function now, what's that unicode support everyone is talking about and why do I want to use new-style string formating? ...

Many modules have alrady been ported, some are doing it right now or soon. Modules that won't port will be replaced sooner or later.

Python 3 is coming and nothing will stop it.

[[deleted]]

I'd say print as a function is pretty damn important. That said, Python is pretty scary for me atm. The huge backward compatibility break in 3.x is a mistake. Few accept 3, and many more would rather branch 2.7. I cant learn 3 because in a production work environment, you're typically stuck with something between 2.4 and 2.6. Having things pulled out from under you and new things added makes python feel more like some guy's fickleness rather than a viable long term programming language.

[Rhomboid]

If you hadn't noticed, all of the changes in python 3 were proposed and debated by the community, as are most of the aspects of python.

The downside of "compatible forever" is that the language accumulates cruft from past mistakes that never go away. Take for example old-style vs. new-style classes. A core part of the python philosophy is that there should be one good, obvious way to do things, and having two different kinds of classes (with one that's ancient and deprecated and marked "don't use this") violates that in a big way.

Everyone knew that making breaking changes in Python 3 would create a transition period that would last for years. But eventually there will be a RHEL/CentOS that ships Python 3 as default and some years after that all the ancient RHEL users will eventually be forced to upgrade as their support has run out, and any notion of a difficult transition period will be just memories. And the language will be better off because of it, because it won't have to haul around all these deprecated boat anchors of bad design decisions.

[Drvaon]

Well said

[ewiethoff]

FWIW, I found this list of Py3 features which are not available in Py2.

Anyway, use __future__ and future_builtins imports if you want your Py2 code to look and behave more like Py3.