cb0ebb9e6c
Third party imports are supposed to be after standard library imports so make six be after. Some newlines are also added to separate standard library imports from all the others. Co-authored-by: Ivan A. Melnikov <imelnikov@griddynamics.com> Change-Id: Ied067e9367612758666da726df195ed390215e1b
80 lines
2.6 KiB
Python
80 lines
2.6 KiB
Python
# -*- coding: utf-8 -*-
|
|
|
|
# vim: tabstop=4 shiftwidth=4 softtabstop=4
|
|
|
|
# Copyright (C) 2012 Yahoo! Inc. All Rights Reserved.
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License"); you may
|
|
# not use this file except in compliance with the License. You may obtain
|
|
# a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
# License for the specific language governing permissions and limitations
|
|
# under the License.
|
|
|
|
import abc
|
|
|
|
import six
|
|
|
|
from taskflow.utils import reflection
|
|
|
|
|
|
@six.add_metaclass(abc.ABCMeta)
|
|
class Flow(object):
|
|
"""The base abstract class of all flow implementations.
|
|
|
|
A flow is a structure that defines relationships between tasks. You can
|
|
add tasks and other flows (as subflows) to the flow, and the flow provides
|
|
a way to implicitly or explicitly define how they are interdependent.
|
|
Exact structure of the relationships is defined by concrete
|
|
implementation, while this class defines common interface and adds
|
|
human-readable (not necessary unique) name.
|
|
|
|
NOTE(harlowja): if a flow is placed in another flow as a subflow, a desired
|
|
way to compose flows together, then it is valid and permissible that during
|
|
execution the subflow & parent flow may be flattened into a new flow. Since
|
|
a flow is just a 'structuring' concept this is typically a behavior that
|
|
should not be worried about (as it is not visible to the user), but it is
|
|
worth mentioning here.
|
|
|
|
Flows are expected to provide the following methods/properties:
|
|
|
|
- add
|
|
- __len__
|
|
- requires
|
|
- provides
|
|
"""
|
|
|
|
def __init__(self, name):
|
|
self._name = str(name)
|
|
|
|
@property
|
|
def name(self):
|
|
"""A non-unique name for this flow (human readable)"""
|
|
return self._name
|
|
|
|
@abc.abstractmethod
|
|
def __len__(self):
|
|
"""Returns how many items are in this flow."""
|
|
|
|
def __str__(self):
|
|
lines = ["%s: %s" % (reflection.get_class_name(self), self.name)]
|
|
lines.append("%s" % (len(self)))
|
|
return "; ".join(lines)
|
|
|
|
@abc.abstractmethod
|
|
def add(self, *items):
|
|
"""Adds a given item/items to this flow."""
|
|
|
|
@abc.abstractproperty
|
|
def requires(self):
|
|
"""Browse argument requirement names this flow requires to run."""
|
|
|
|
@abc.abstractproperty
|
|
def provides(self):
|
|
"""Browse argument names provided by the flow."""
|