Source code for cement.core.interface

Cement core interface module.

from abc import ABC
from ..core import exc, meta
from ..utils.misc import minimal_logger

LOG = minimal_logger(__name__)

[docs] class Interface(ABC, meta.MetaMixin): """Base interface class that all Cement Interfaces should subclass from."""
[docs] class Meta: """ Interface meta-data (can also be passed as keyword arguments to the parent class). """ interface = NotImplemented """The string identifier of this interface."""
def __init__(self, **kw): super(Interface, self).__init__(**kw) try: assert self._meta.interface, \ "%s.Meta.interface undefined." % self.__class__.__name__ except AssertionError as e: raise exc.InterfaceError(e.args[0])
[docs] def _validate(self): """ Perform any validation to ensure proper data, meta-data, etc. """ pass
[docs] class InterfaceManager(object): """ Manages the interface system to define, get, list interfaces with the Cement Framework. """ def __init__(self, app): = app self.__interfaces__ = {}
[docs] def get(self, interface, fallback=None, **kwargs): """ Get an interface class. Args: interface (str): The interface label (i.e. ``output``) fallback (Handler): A fallback value to return if ``interface`` doesn't exist. Returns: Interface: An uninstantiated interface class Raises: cement.core.exc.InterfaceError: If the ``interface`` does not exist. Example: .. code-block:: python i = app.interface.get('output') """ if interface in self.__interfaces__.keys(): return self.__interfaces__[interface] elif fallback is not None: return fallback else: raise exc.InterfaceError("interface '%s' does not exist!" % interface)
[docs] def list(self): """ Return a list of defined interfaces. Returns: list: Interface labels. Example: .. code-block:: python app.interface.list() """ return list(self.__interfaces__.keys())
[docs] def define(self, ibc): """ Define an ``ibc`` (interface base class). Args: ibc (Interface): The abstract base class that defines the interface Raises: cement.core.exc.InterfaceError: If the interface label is already defined Example: .. code-block:: python app.interface.define(DatabaseInterface) """ LOG.debug("defining interface '%s' (%s)" % (ibc.Meta.interface, ibc.__name__)) if ibc.Meta.interface in self.__interfaces__: msg = "interface '%s' already defined!" % ibc.Meta.interface raise exc.InterfaceError(msg) self.__interfaces__[ibc.Meta.interface] = ibc
[docs] def defined(self, interface): """ Test whether ``interface`` is defined. Args: interface (str): The label of the interface (I.e. ``log``, ``config``, ``output``, etc). Returns: bool: ``True`` if the interface is defined, ``False`` otherwise Example: .. code-block:: python app.interface.defined('log') """ if interface in self.__interfaces__: return True else: return False