Phlow
Phlow is the framework used in Glamorous Toolkit to define inspectors. Every action (the buttons on the top right of an inspector) and every view (the tabs inside the inspector) are defined using Phlow concepts.
As described above, phlow has two major concepts: Inspector views and Inspector actions. These are defined on the object as methods, and then queried by the inspector to find out how it should present itself.
To query views, you can try executing:
#gtView gtPragmas
Likewise, you can query actions:
#gtAction gtPragmas
As Phlow is largely a description of how these views should behave, it can exist in other languages. Phlow for Python is an example of such an implementation, and Inspecting remote objects using Remote Phlow shows the general mechanism behind it. For the native parts of Glamorous Toolkit written in Rust, an implementation for Rust was created, and Identifying an editor bug by inspecting wrapped Rust objects is a case study for it.