Simon Willison’s Weblog

Exciting stuff in Python 2.5

Python 2.5 alpha 1 is out, and as usual the What’s New in Python 2.5 document provides a pleasant overview of the new features. There are some real treats in there. While I’m hoping that the syntax for conditional expressions will grow on me, I’m looking forward to Partial function application becoming a common Python idiom. Relative imports are going to make Django applications a lot easier to redistribute, and I can’t wait to see all the crazy hacks that result from the introduction of coroutines.

I’ve seen David Heinemeier Hansson speak a few times, and he often uses ActiveRecord’s transaction support to illustrate the elegance that well-written Ruby has to offer:

Account.transaction(account1, account2) do
  account1.withdraw(100)
  account2.deposit(100)
end

Here a Ruby block is being used as syntax for a database transaction, guaranteeing that some code will be run before and after the withdraw and deposit lines. The new with statement makes something similar possible with an imaginary Python ORM:

with Account.transaction(account1, account2):
    account1.withdraw(100)
    account2.deposit(100)

The highlight of the release might well be the modules that have been added to the standard library—tucked away in section 13 of the document. ctypes, ElementTree, a new hashlib with support for SHA-224 through 512 and sqlite3 (a renamed pysqlite) are all included. ctypes is particularly interesting as it lets you call functions in compiled DLLs and shared libraries without having to compile a Python wrapper.

The final Python 2.5 release appears to be scheduled for June-July this year, which should give Apple ample time to incorporate it in to OS X Leopard.