History of Dectate
Dectate was extracted from Morepath and then extensively refactored and cleaned up. It is authored by me, Martijn Faassen.
In the beginning (around 2001) there was zope.configuration, part of the Zope 3 project. It features declarative XML configuration with conflict detection and overrides to assemble pieces of Python code.
In 2006, I helped create the Grok project. This did away with the XML based configuration and instead used Python code. This in turn then drove zope.configuration. Grok did not use Python decorators but instead used specially annotated Python classes, which were recursively scanned from modules. Grok's configuration system was spun off as the Martian library.
Chris McDonough was then inspired by Martian to create Venusian, a deferred decorator execution system. It is like Martian in that it imports Python modules recursively in order to find configuration.
I created the Morepath web framework, which uses decorators for configuration throughout and used Venusian. Morepath grew a configuration subsystem where configuration is associated with classes, and uses class inheritance to power configuration reuse and overrides. This configuration subsystem started to get a bit messy as requirements grew.
So in 2016 I extracted the configuration system from Morepath into its own library, Dectate. This allowed me to extensively refactor the code for clarity and features. Dectate does not use Venusian for configuration. Dectate still defers the execution of configuration actions to an explicit commit phase, so that conflict detection and overrides and such can take place.