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from dlab_core.containers import Container
from dlab_core.dispatchers import EventDispatcher
from dlab_core.domain.exceptions import DLabException
__all__ = ['add_hook', 'do_action', 'load_context',
'reload_context', 'extend_context', 'freeze_context',
'get_resource', 'register_context', 'RegistryLoadException',
'CONTAINER_PARAM_CORE_CLI_ROUTERS']
LC_ERR_PLUGIN_LOADED = 'Plugin "{name}" already loaded.'
"""Container parameter name for event dispatcher in global scope."""
CONTAINER_PARAM_EVENT_DISPATCHER = 'event_dispatcher'
"""Container parameter name for event dispatcher in global scope."""
[docs]CONTAINER_PARAM_CORE_CLI_ROUTERS = 'core.cli_router'
context = Container()
[docs]class RegistryLoadException(DLabException):
pass
[docs]def register_context(key, value):
"""Sets a parameter or an object. Objects must be defined as Closures.
Allowing any python callable leads to difficult to debug problems as
function names (strings) are callable (creating a function with the
same name as an existing parameter would break your container).
:type key: str
:param key: The unique identifier for the parameter or object.
:param value: The value or a closure of the parameter.
"""
context[key] = value
[docs]def extend_context(key, call):
"""Extends an object definition. Useful when you want to extend an
existing object definition, without necessarily loading that object.
:type key: string
:param key: The unique identifier for the parameter or object.
:type call: callable
:param call: The passed callable.
:rtype: callable
:return: The wrapped callable.
"""
context.extend(key, call)
[docs]def freeze_context(key, call):
"""Protects a callable from being interpreted as a service. This is
useful when you want to store a callable as a parameter.
:type key: string
:param key: The unique identifier for the parameter or object.
:type call: function
:param call: A callable to protect from being evaluated.
:rtype: callable
:return: The passed callable.
"""
context.protect(call)
register_context(key, call)
[docs]def get_resource(key):
"""Returns the context resource at the specified index.
:type key: string
:param key: The unique identifier for the parameter or object.
:return: Resource parameter or an object.
"""
return context[key]
[docs]def load_context():
"""Initial Load base context resources."""
register_context(
CONTAINER_PARAM_EVENT_DISPATCHER, lambda c: EventDispatcher())
[docs]def reload_context():
"""Reload base context resources."""
context.clear()
load_context()
[docs]def do_action(name):
"""This function invokes all functions attached to hook action.
Hooks needs to have next naming convention <verb>.<noun>
:type name: str
:param name: Action name.
"""
def wrapper(func):
def wrapped(*args, **kwargs):
dispatcher = get_resource(CONTAINER_PARAM_EVENT_DISPATCHER)
dispatcher.dispatch(name)
return func(*args, **kwargs)
return wrapped
return wrapper
[docs]def add_hook(name, call):
"""Actions are the hooks that the core launches at specific points during
execution, or when specific events occur. Plugins can specify that one or
more of its Python functions are executed at these points, using the
Action API.
It is possible to create new action hooks by simply calling this function,
specifying the name of the new hook using the name parameter.
Hooks needs to have next naming convention <verb>.<noun>
:type name: str
:param name: Action name.
:type call: callable
:param call: Code automatically invokes whenever a special action occurs.
"""
context[CONTAINER_PARAM_EVENT_DISPATCHER].add_listener(name, call)