Discovery of custom backends¶

A tripper backend is a normal importable Python module that defines the class {Name}Strategy, where {Name} is the name of the backend with the first letter capitalized (as it would be with the str.title() method). The methods they are supposed to define are documented in tripper/interface.py.

Tripper support several use cases for discovery of custom backends.

Installed backend package¶

It is possible to create a pip installable Python package that provides new tripper backends that will be automatically discovered.

The backend package should add the following to its pyproject.toml file:

[project.entry-points."tripper.backends"]
mybackend1 = "subpackage.mybackend1"
mybackend2 = "subpackage.mybackend2"

When your package is installed, this would make mybackend1 and mybackend2 automatically discovarable by tripper, such that you can write

>>> from tripper import Triplestore
>>> ts = Triplestore(backend="mybackend1")

Backend module¶

If you have a tripper backend that is specific to your application, or that you for some other reason don't want or feel the need to publish as a separate Python package, you can keep the backend as a module within your application.

In this case you have two options, either specify explicitly backend module when you instantiate your triplestore or append your package to the tripper.backend_packages module variable:

Instantiate triplestore with explicit module path¶

An explicit module path can either be absolute or relative as shown in the example below:

# Absolute
>>> ts = Triplestore(backend="mypackage.backends.mybackend")

# Relative to the `package` argument
>>> ts = Triplestore(backend="backends.mybackend", package="mypackage")

A backend is considered to be specified explicitly if the backend argument contain a dot (.) or if the package argument is provided.

Append to `tripper.backend_packages`¶

Finally you can insert/append the sub-package with your backend to the tripper.backend_packages list module variable:

import tripper
tripper.backend_packages.append("mypackage.backends")
ts = Triplestore(backend="mybackend")

Search order for backends¶

Tripper backends are looked up in the following order: 1. explicit specified backend modules 2. backend packages 3. checking tripper.backend_packages

By default the built-in backends are looked up as the first element in tripper.backend_packages (but it is possible for the insert a custom backend sub-package before it). This means that backend packages are looked up before the built-in backends. Hence it is possible for a backend package to overwrite or extend a built-in backend.