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Decorator for validating and caching values returning from methods.

Project description

Module objectvalidator provides functionality for validating and caching values returned from methods.

Instalation

cd objectvalidator/
python setup.py install

Usage

option decorator validates and caches values returned from methods. Can be used either with arguments or without. If arguments are ommited, value is not validated, only cached. Allowed arguments are required and attrtype. If required is True, value returned from method mustn’t be None. attrtype is a type which is allowed for value. Can be either single type or tuple containig types.

@option
def foo(self):
    return ...

@option(required=True, attrtype=int)
def bar(self):
    return ...

@option(required=True, attrtype=(int, float))
def baz(self):
    return ...

option.get_option_names(inst) returns list containig method’s names on inst instance which are decorated by option decorator.

option.load_all_options(inst) tries reading values from all methods on inst instance which are decorated by option decorator. Reading will cause validation of theese values and cache them.

OptionsContainer class is a container for options methods. During initialization values from all methods decorated by option decorator are read . So if class is successfuly initialized, all options are valid a cached.

OptionsContainer.initialize(*args, **kwargs) initializes instance attributes. You can override this method in the subclasses.

Example

    import os

from objectvalidator import option, OptionsContainer

SETTINGS = {
    'NAME': 'ExampleApp',
    'DATABASE': {
        'db': 'exampleapp_db',
        'host': 'localhost',
        'port': 3306,
        'user': 'exampleapp-rw',
        'password': 'a8RnU43A',
    },
}


class Config(OptionsContainer):

    def initialize(self, settings):
        self._settings = settings

    @option(required=True, attrtype=str)
    def name(self):
        return self._settings['NAME']

    @option
    def database(self):
        return DatabaseConfig(self._settings['DATABASE'])


class DatabaseConfig(OptionsContainer):

    def initialize(self, database_settings):
        self._database_settings = database_settings

    @option(required=True, attrtype=str)
    def db(self):
        db = os.environ.get('DATABASE_DB')
        if db is not None:
            return db
        return self._database_settings['db']

    @option(required=True, attrtype=str)
    def host(self):
        host = os.environ.get('DATABASE_HOST')
        if host is not None:
            return host
        return self._database_settings['host']

    @option(required=True, attrtype=int)
    def port(self):
        port = os.environ.get('DATABASE_PORT')
        if port is not None:
            return int(port)
        return self._database_settings.get('port', 3306)

    @option(required=True, attrtype=str)
    def user(self):
        user = os.environ.get('DATABASE_USER')
        if user is not None:
            return user
        return self._database_settings['user']

    @option(required=True, attrtype=str)
    def password(self):
        password = os.environ.get('DATABASE_PASSWORD')
        if password is not None:
            return password
        return self._database_settings['password']


>>> config = Config(SETTINGS)
>>> config.name
'ExampleApp'
>>> config.database
<DatabaseConfig: db='exampleapp_db', host='localhost', ...>
>>> config.database.db
'exampleapp_db'
>>> option.get_option_names(config)
['database', 'name']

License

3-clause BSD

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