Minimum Python Version

The minimum Python version required for Marrow projects, including WebCore, has been bumped to Python 3.6, released December 23, 2016.

Reason as to why everything's been bumped up to 3.6: we have begun utilizing some of the features introduced in that version and prior Python 3 versions extensively, such as literal string interpolation / format strings. The benefits / things to keep in mind for 3.6 include:

• PEP 468, preserving keyword argument order.

• PEP 487, simpler customization of class creation. The availability of __init_subclass__ obsoletes marrow.schema's implementation of the same base functionality in the __attributed__ @classmethod callback.

• PEP 498, literal string interpolation. "Format strings" or "f-strings". Praise be to baby {romulus} and {remus}, yes.

• PEP 506, adding a secrets module to the standard library. Please stop using the "random" module for anything important.

• PEP 520, preserving class attribute (and dictionary!) definition order. Obsoletes marrow.schema's __sequence__ implementation of that functionality, and the need for ordered mappings (e.g. Attributes) to be pre-calculated.

• PEP 526, syntax for variable annotations (provisional).

• PEP 528 (console encoding) and PEP 529 (filesystem encoding) defaulting to utf-8 welcomes Microsoft Windows into the wider internet ecosystem on encoding standardization.

• PEP 525 asynchronous generators and PEP 530 asynchronous comprehensions.

From older versions; 3.5:

• PEP 484 type hints and the introduction of the typing module.

• PEP 448 additional unpacking generalizations. (Multiple argument unpacks in one invocation.)

• .hex() methods on bytes, bytearray, and memoryview instances.

• collections.OrderedDict is now C-backed, 4x-100x faster.

• traceback module enhancements.

From older versions; 3.4:

• codec improvements.

• asyncio API and module.

• PEP 435 enum module and type.

• PEP 450 a basic numerically stable statistics library.

• E-mail improvements.

From older versions; 3.3:

• Core ipaddress type.

• venv introduced.

From older versions; 3.2:

There's a ton in here.

• PEP 391, dictionary-based logging configuration.

• PEP 3148, concurrent.futures.

• PEP 3333, Python Web Server Gateway Interface version 1.0.1.

• Even more e-mail improvements.