Python 3.5 Brings New Language Features and Library Modules

Recently released Python 3.5 brings a host of changes, including several new syntax features, new library modules, improvements to the standard library, and to security.

Syntax features

Python 3.5 introduces three new syntactic features:

• coroutines with async-await syntax, which allows developers to write code as if it were sequential. In fact, the compiler will implement it through a sequence of coroutines, thus making it effectively concurrent. In the following example, multiple await statements can be thought of as executing sequentially, but they would not cause any actual block:

  async def read_data(db):
  data = await db.fetch('SELECT ...')
  if (data...)
      await api.send(data ...')
  

• a matrix multiplication operator that allows to express the multiplication between matrices as a @ b. This will allow to write:

  S = (H @ beta - r).T @ inv(H @ V @ H.T) @ (H @ beta - r)
  

  instead of:

  S = dot((dot(H, beta) - r).T, dot(inv(dot(dot(H, V), H.T)), dot(H, beta) - r))
  	

• unpacking generalization, which is meant to extend the allowed usage of the * unpacking operator and make it possible to use it multiple times in function calls, or inside of tuples:

  >>> print(*[1], *[2], 3)
  1 2 3
  >>> dict(**{'x': 1}, y=2, **{'z': 3})
  {'x': 1, 'y': 2, 'z': 3}
  
  
  >>> *range(4), 4
  (0, 1, 2, 3, 4)
  

Library Modules

New library modules in Python 3.5 introduce:

• type hints, which aim to enable type checking annotations to 3rd party modules while also allowing unaltered execution if desired.
• new zipapp module provides an API and command line tool for creating executable Python Zip Applications.

Other changes brought by Python 3.5 include:

• new C-implementations of collections.OrderedDict and functools.lru_cache() with much improved performance;
• new os.scandir() that allows faster directory transversal.

Additionally, SSLv3 has been disabled by default, although it can be enabled if required.