Writing a Nautilus-Python extension is a fairly straight-forward process. One simply imports the Nautilus module from the gobject introspection repository and creates a class which is derived from a gobject.GObject and one of the Nautilus module's classes. When an extension derives a class, it becomes a "provider", telling Nautilus to ask it for information. There are several types of providers available for extensions to use: there is MenuProvider, LocationWidgetProvider, ColumnProvider, PropertyPageProvider, and InfoProvider, all of which will be explained in more detail below. Your class can be derived from multiple providers.
Here are the basic steps:
1. A script is written and installed to the standard nautilus-python extension install path
2. Nautilus is (re)started and loads the nautilus-python C extension, which in turn loads all python extensions it can find
3. Any python script in the standard nautilus-python extension install path that imports the Nautilus module from the gobject introspection repository and derives the main class from a Nautilus module class will be loaded
As of nautilus-python 0.7.0 (and continued in 1.0+), nautilus-python looks in ~/.local/share/nautilus-python/extensions for local extensions and $PREFIX/share/nautilus-python/extensions for global extensions.
1. We no longer support the "import nautilus" command that previous versions used. This is because nautilus-python now directly uses Nautilus's annotations, which must be imported by the "from gi.repository import Nautilus" command.
2. The extension class must now derive itself from a gobject.GObject in addition to the standard Nautilus classes.
3. For now, some Nautilus class constructors require passing named arguments instead of a standard argument list. This requirement may go away at some point.