More information on the project website https://www.e2immu.org.
e2immu is a static code analyser for modern Java. As for every code analyser, it aims to help you write better code by making you aware of unwanted constructs, possible causes for exceptions etc. Even if it includes many "standard" warnings, e2immu is not a general code analyser: it focuses on modification and immutability. It is able to detect that classes are immutable in practice, or not, and why they are not.
It also provides a practical definition of such immutability, called "effective immutability". It can detect that classes are eventually immutable, i.e., they become effectively immutable after an initialisation phase. It provides some out-of-the-box classes that help with making your own code eventually immutable.
Ideally, the results of the analyser are shown directly in your programming environment. At the moment, a plugin for IntelliJ is in development. Support for Eclipse and Visual Studio Code are planned.
The following links point towards in-depth reading material:
- The Road to Immutability A gentle introduction to the concepts of effective and eventual immutability
- e2immu manual The manual of the e2immu project.
TL;DR: The e2immu analyser is not yet ready for general use. Please follow the project on GitHub to stay in touch if you "just" want to use the analyser.
All core concepts are solid, however. There is a full tutorial about the how and why of effective and eventual immutability, and all related properties. There are more than 250 code snippets running green, so there is a ton of example material already present. You can already improve your code by introducing eventually immutable constructs. The analyser is "nothing but" a support tool to help you along.
In descending order of priority, we are now focusing on
- fixing bugs and crashes;
- enabling the analyser to process its own code base. This partially depends on advances in the JavaParser library, since the analyser uses Java 16 syntax and constructs;
- providing one working, informative IDE plugin;
- determining a selection of the most important Java APIs, and providing annotations for them.
As soon as these four milestones have been met, the analyser will be promoted as "ready for general use".