Plugin Loaders

Currently, three simple loaders are provided.


The recommended loader is the ClassLoader, used to load all the classes from all of the modules in the namespace given. Optionally, you can pass a subclasses parameter to load(), which will filter the loaded classes to those which are a sub-class of any given type.

For example,

import os
from straight.plugin.loaders import ClassLoader
from myapp import FileHandler

plugins = ClassLoader().load('myplugins', subclasses=FileHandler)

for filename in os.listdir('.'):
    for handler_cls in plugins:
        handler = handler_cls(filename)
        if handler.valid():

However, it is preferred that you use the load() helper provided.

from straight.plugin import load

plugins = load('myplugins', subclasses=FileHandler)

This will automatically use the ClassLoader when given a subclasses argument.


Before anything else, straight.plugin loads modules. The ModuleLoader is used to do this.

from straight.plugin.loaders import ModuleLoader

plugins = ModuleLoader().load('myplugins')

A note about PEP-420:

Python 3.3 will support a new type of package, the Namespace Package. This allows language-level support for the namespaces that make straight.plugin work and when 3.3 lands, you can create addition plugins to be found in a namespace. For now, continue to use the pkgutil boilerplate, but when 3.3 is released, straight.plugin already supports both forms of namespace package!


If you need to combine multiple plugins inside each module, you can load all the objects from the modules, rather than the modules themselves.

from straight.plugin.loaders import ObjectLoader

plugins = ObjectLoader().load('myplugins')