Compare Polymer vs. zope.interface

The Polymer library offers a robust set of functionalities for developing custom elements, streamlining the process to ensure they behave like standard DOM elements. Just like conventional DOM elements, Polymer elements can be created through a constructor or by utilizing document creation methods, and they can be configured via attributes or properties. Each instance can contain an internal DOM, adapt to changes in properties and attributes, and receive styling both from internal defaults and external sources, all while responding to methods that alter their internal state. When you register a custom element, you link a class to a specific custom element name, and the element includes lifecycle callbacks to effectively manage its various stages. Additionally, Polymer facilitates property declarations, allowing for seamless integration of your element's property API with the Polymer data system. By employing Shadow DOM, your element gains a locally scoped and encapsulated DOM tree, and Polymer can automatically generate and fill a shadow tree for your element derived from a DOM template, enhancing the modularity and reusability of your code. This combination of features not only simplifies the creation of custom elements but also ensures they integrate smoothly into the wider ecosystem of web components.

This package is designed for independent reuse across any Python project and is maintained by the Zope Toolkit initiative. It serves as an implementation of "object interfaces" within the Python ecosystem. Interfaces act as a way to designate objects as adhering to a specific API or contract, making this package a practical example of applying the Design By Contract methodology in Python. Essentially, interfaces are objects that detail (document) the expected external behavior of the objects that implement them. An interface articulates behavior through a combination of informal documentation within a docstring, attribute definitions, and invariants, which are the necessary conditions that must be satisfied by the objects implementing the interface. Attribute definitions specify particular attributes, outlining their names while offering documentation and constraints regarding the allowed values for those attributes. These definitions can take various forms, allowing for flexibility in how they are expressed. Furthermore, the ability to define interfaces enhances the clarity and reliability of code by ensuring that objects conform to specified behaviors.