shellbot.context module

class shellbot.context.Context(settings=None, filter=None)

Bases: object

Stores settings across multiple independent processing units

This is a key-value store, that supports concurrency across multiple processes.

apply(settings={})

Applies multiple settings at once

Parameters:settings (dict) – variables to be added to this context

check(key, default=None, is_mandatory=False, validate=None, filter=False)

Checks some settings

Parameters:

• key – the key that has to be checked
• default (str) – the default value if no statement can be found
• is_mandatory (bool) – raise an exception if keys are not found
• validate (callable) – a function called to validate values before the import
• filter (bool) – look at the content, and change it eventually

Example:

context = Context({
    'spark': {
        'room': 'My preferred room',
        'participants':
            ['alan.droit@azerty.org', 'bob.nard@support.tv'],
        'team': 'Anchor team',
        'token': 'hkNWEtMJNkODk3ZDZLOGQ0OVGlZWU1NmYtyY>',
        'webhook': "http://73a1e282.ngrok.io",
        'weird_token', '$WEIRD_TOKEN',
    }
})

context.check('spark.room', is_mandatory=True)
context.check('spark.team')
context.check('spark.weird_token', filter=True)

When a default value is provided, it is used to initialize properly a missing key:

context.check('general.switch', 'on')

Another usage is to ensure that a key has been set:

context.check('spark.room', is_mandatory=True)

Additional control can be added with the validation function:

context.check('general.switch',
              validate=lambda x: x in ('on', 'off'))

When filter is True, if the value is a string starting with ‘$’, then a variable with the same name is loaded from the environment:

>>>token=context.check('spark.weird_token', filter=True)
>>>assert token == os.environ.get('WEIRD_TOKEN')
True

The default filter can be changed at the creation of a context:

>>>context=Context(filter=lambda x : x + '...')

This function raises KeyError if a mandatory key is absent. If a validation function is provided, then a ValueError can be raised as well in some situations.

clear()

Clears content of a context

decrement(key, delta=1)

Decrements a value

get(key, default=None)

Retrieves the value of one configurationkey

Parameters:

• key (str) – name of the value
• default (any serializable type is accepted) – default value

Returns:

the actual value, or the default value, or None

Example:

message = context.get('bot.on_start')

This function is safe on multiprocessing and multithreading.

has(prefix)

Checks the presence of some prefix

Parameters:prefix (str) – key prefix to be checked Returns:True if one or more key start with the prefix, else False

This function looks at keys actually used in this context, and return True if prefix is found. Else it returns False.

Example:

context = Context(settings={'space': {'title', 'a title'}})

>>>context.has('space')
True

>>>context.has('space.title')
True

>>>context.has('spark')
False

increment(key, delta=1)

Increments a value

is_empty

Does the context store something?

Returns:True if there at least one value, False otherwise

set(key, value)

Changes the value of one configuration key

Parameters:

• key (str) – name of the value
• value (any serializable type is accepted) – new value

Example:

context.set('bot.on_start', 'hello world')

This function is safe on multiprocessing and multithreading.

classmethod set_logger(level=10)

Configure logging

Parameters:level – expected level of verbosity

This utility function should probably be put elsewhere