7f0c457e72
Optional arguments that are not explicitly required are being ignored when arguments are being mapped based on inference from atoms' execute method signatures. This patch adds support for mapping optional arguments in addition to required arguments. Change-Id: I440c02dcd901a563df512e33754b13e3c05d4155
228 lines
9.5 KiB
Python
228 lines
9.5 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2013 Rackspace Hosting Inc. All Rights Reserved.
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# Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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from oslo_utils import reflection
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import six
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from taskflow import exceptions
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from taskflow.utils import misc
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def _save_as_to_mapping(save_as):
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"""Convert save_as to mapping name => index.
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Result should follow storage convention for mappings.
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"""
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# TODO(harlowja): we should probably document this behavior & convention
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# outside of code so that it's more easily understandable, since what an
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# atom returns is pretty crucial for other later operations.
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if save_as is None:
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return {}
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if isinstance(save_as, six.string_types):
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# NOTE(harlowja): this means that your atom will only return one item
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# instead of a dictionary-like object or a indexable object (like a
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# list or tuple).
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return {save_as: None}
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elif isinstance(save_as, (tuple, list)):
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# NOTE(harlowja): this means that your atom will return a indexable
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# object, like a list or tuple and the results can be mapped by index
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# to that tuple/list that is returned for others to use.
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return dict((key, num) for num, key in enumerate(save_as))
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elif isinstance(save_as, set):
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# NOTE(harlowja): in the case where a set is given we will not be
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# able to determine the numeric ordering in a reliable way (since it is
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# a unordered set) so the only way for us to easily map the result of
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# the atom will be via the key itself.
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return dict((key, key) for key in save_as)
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raise TypeError('Atom provides parameter '
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'should be str, set or tuple/list, not %r' % save_as)
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def _build_rebind_dict(args, rebind_args):
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"""Build a argument remapping/rebinding dictionary.
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This dictionary allows an atom to declare that it will take a needed
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requirement bound to a given name with another name instead (mapping the
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new name onto the required name).
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"""
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if rebind_args is None:
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return {}
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elif isinstance(rebind_args, (list, tuple)):
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rebind = dict(zip(args, rebind_args))
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if len(args) < len(rebind_args):
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rebind.update((a, a) for a in rebind_args[len(args):])
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return rebind
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elif isinstance(rebind_args, dict):
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return rebind_args
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else:
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raise TypeError("Invalid rebind value '%s' (%s)"
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% (rebind_args, type(rebind_args)))
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def _build_arg_mapping(atom_name, reqs, rebind_args, function, do_infer,
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ignore_list=None):
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"""Builds an input argument mapping for a given function.
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Given a function, its requirements and a rebind mapping this helper
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function will build the correct argument mapping for the given function as
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well as verify that the final argument mapping does not have missing or
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extra arguments (where applicable).
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"""
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# build a list of required arguments based on function signature
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req_args = reflection.get_callable_args(function, required_only=True)
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all_args = reflection.get_callable_args(function, required_only=False)
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# remove arguments that are part of ignore_list
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if ignore_list:
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for arg in ignore_list:
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if arg in req_args:
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req_args.remove(arg)
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else:
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ignore_list = []
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required = {}
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# add reqs to required mappings
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if reqs:
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required.update((a, a) for a in reqs)
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# add req_args to required mappings if do_infer is set
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if do_infer:
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required.update((a, a) for a in req_args)
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# update required mappings based on rebind_args
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required.update(_build_rebind_dict(req_args, rebind_args))
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if do_infer:
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opt_args = set(all_args) - set(required) - set(ignore_list)
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optional = dict((a, a) for a in opt_args)
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else:
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optional = {}
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if not reflection.accepts_kwargs(function):
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extra_args = set(required) - set(all_args)
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if extra_args:
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extra_args_str = ', '.join(sorted(extra_args))
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raise ValueError('Extra arguments given to atom %s: %s'
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% (atom_name, extra_args_str))
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# NOTE(imelnikov): don't use set to preserve order in error message
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missing_args = [arg for arg in req_args if arg not in required]
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if missing_args:
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raise ValueError('Missing arguments for atom %s: %s'
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% (atom_name, ' ,'.join(missing_args)))
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return required, optional
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class Atom(object):
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"""An abstract flow atom that causes a flow to progress (in some manner).
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An atom is a named object that operates with input flow data to perform
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some action that furthers the overall flows progress. It usually also
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produces some of its own named output as a result of this process.
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:ivar version: An *immutable* version that associates version information
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with this atom. It can be useful in resuming older versions
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of atoms. Standard major, minor versioning concepts
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should apply.
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:ivar save_as: An *immutable* output ``resource`` name dictionary this atom
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produces that other atoms may depend on this atom providing.
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The format is output index (or key when a dictionary
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is returned from the execute method) to stored argument
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name.
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:ivar rebind: An *immutable* input ``resource`` mapping dictionary that
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can be used to alter the inputs given to this atom. It is
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typically used for mapping a prior atoms output into
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the names that this atom expects (in a way this is like
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remapping a namespace of another atom into the namespace
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of this atom).
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:param name: Meaningful name for this atom, should be something that is
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distinguishable and understandable for notification,
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debugging, storing and any other similar purposes.
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:param provides: A set, string or list of items that
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this will be providing (or could provide) to others, used
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to correlate and associate the thing/s this atom
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produces, if it produces anything at all.
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:param inject: An *immutable* input_name => value dictionary which
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specifies any initial inputs that should be automatically
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injected into the atoms scope before the atom execution
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commences (this allows for providing atom *local* values that
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do not need to be provided by other atoms/dependents).
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:ivar inject: See parameter ``inject``.
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:ivar requires: Any inputs this atom requires to function (if applicable).
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NOTE(harlowja): there can be no intersection between what
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this atom requires and what it produces (since this would
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be an impossible dependency to satisfy).
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:ivar optional: Any inputs that are optional for this atom's execute
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method.
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"""
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def __init__(self, name=None, provides=None, inject=None):
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self._name = name
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self.save_as = _save_as_to_mapping(provides)
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self.version = (1, 0)
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self.inject = inject
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self.requires = frozenset()
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self.optional = frozenset()
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def _build_arg_mapping(self, executor, requires=None, rebind=None,
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auto_extract=True, ignore_list=None):
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req_arg, opt_arg = _build_arg_mapping(self.name, requires, rebind,
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executor, auto_extract,
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ignore_list)
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self.rebind = {}
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if opt_arg:
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self.rebind.update(opt_arg)
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if req_arg:
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self.rebind.update(req_arg)
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self.requires = frozenset(req_arg.values())
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self.optional = frozenset(opt_arg.values())
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if self.inject:
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inject_set = set(six.iterkeys(self.inject))
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self.requires -= inject_set
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self.optional -= inject_set
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out_of_order = self.provides.intersection(self.requires)
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if out_of_order:
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raise exceptions.DependencyFailure(
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"Atom %(item)s provides %(oo)s that are required "
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"by this atom"
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% dict(item=self.name, oo=sorted(out_of_order)))
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@property
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def name(self):
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"""A non-unique name for this atom (human readable)."""
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return self._name
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def __str__(self):
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return "%s==%s" % (self.name, misc.get_version_string(self))
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def __repr__(self):
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return '<%s %s>' % (reflection.get_class_name(self), self)
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@property
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def provides(self):
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"""Any outputs this atom produces.
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NOTE(harlowja): there can be no intersection between what this atom
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requires and what it produces (since this would be an impossible
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dependency to satisfy).
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"""
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return set(self.save_as)
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