Py-Context

Python dict with stacked context data

• Free software: MIT license
• GitHub: https://github.com/dealertrack/py-context

Installing

You can install py-context using pip:

$ pip install py-context

Example

>>> context = Context({'user': 'Fred', 'city': 'Bedrock'})
>>> context['user']
'Fred'
>>> context['city']
'Bedrock'
>>> context.push({'user': 'Barney'})
>>> context['user']
'Barney'
>>> context['city']
'Bedrock'
>>> context.pop()
{'user': 'Barney'}
>>> context['user']
'Fred'

Context also supports signals. Signal handler can be attached globally:

>>> @context_key_changed.connect
... def handler(sender, context, key, new, old):
...     print(key, new, old)

>>> context = Context()
>>> context['hello'] = 'world'
hello world <Missing>

Or to individual context instances:

>>> def handler(sender, context, key, new, old):
...     print(key, new, old)
>>> context = Context()
>>> context_key_changed.connect(handler, sender=context)

Supported signals:

>>> @context_initialized.connect
... def handler(sender, context):
...     pass

>>> @pre_context_changed.connect
... def handler(sender, context):
...     pass

>>> @post_context_changed.connect
... def handler(sender, context):
...     pass

>>> @context_key_changed.connect
... def handler(sender, context, key, new, old):
...     pass

Additionally, ClassSignallingContext can be used to subscribe signals by sender classes, not instances:

>>> class TestContext(ClassSignallingContext):
...     pass
>>> def context_key_changed_handler(sender, context, key, new, old):
...     print(key, new, old)
>>> _ = context_key_changed.connect(context_key_changed_handler, sender=TestContext)

>>> context = Context()
>>> class_context = TestContext()

>>> context['foo'] = 'bar'
>>> class_context['foo'] = 'bar'
foo bar <Missing>

Testing

To run the tests you need to install testing requirements first:

$ make install

Then to run tests, you can use nosetests or simply use Makefile command:

$ nosetests -sv
# or
$ make test