d1a88bad18
Add a new way of formatting our output in a consistent way. This turns print_list and print_dict into a formatter that has the same API as any other formatter and allows users to create their own formatters and plug them into cratonclient. This includes tests for the base level formatter and our two default formatters as well as some refactoring to allow users to specify their own --format. At the moment, however, the subcommand shells do *not* use the pluggable formatter decided by the user. That change and all of the downstream effects it has on testing is going to be *very* significant and deserves its own commit as this one is large enough. Change-Id: I6649ebce57d5ddf2d4aeb689e77e3c17ef3a2e97
108 lines
3.6 KiB
Python
108 lines
3.6 KiB
Python
# 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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"""Base class implementation for formatting plugins."""
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from cratonclient import crud
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class Formatter(object):
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"""Class that defines the formatter interface.
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Instead of having to override and call up to this class's ``__init__``
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method, we also provide an ``after_init`` method that can be implemented
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to extend what happens on initialization.
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.. attribute:: args
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Parsed command-line arguments stored as an instance of
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:class:`argparse.Namespace`.
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"""
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def __init__(self, parsed_args):
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"""Instantiate our formatter with the parsed CLI arguments.
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:param parsed_args:
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The CLI arguments parsed by :mod:`argparse`.
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:type parsed_args:
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argparse.Namespace
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"""
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self.args = parsed_args
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self.after_init()
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def after_init(self):
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"""Initialize the object further after ``__init__``."""
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pass
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def configure(self, *args, **kwargs):
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"""Optional configuration of the plugin after instantiation."""
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return self
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def handle(self, item_to_format):
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"""Handle a returned item from the cratonclient API.
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cratonclient's API produces both single Resource objects as well as
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generators of those objects. This method should be capable of handling
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both.
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Based on the type, this will either call ``handle_generator`` or
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``handle_instance``. Subclasses must implement both of those methods.
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:returns:
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None
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:rtype:
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None
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:raises ValueError:
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If the item provided is not a subclass of
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:class:`~cratonclient.crud.Resource` or an iterable class then
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we will not know how to handle it. In that case, we will raise a
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ValueError.
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"""
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if isinstance(item_to_format, crud.Resource):
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self.handle_instance(item_to_format)
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return
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try:
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self.handle_generator(item_to_format)
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except TypeError as err:
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raise ValueError(
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"Expected an iterable object but instead received something "
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"of type: %s. Received a TypeError: %s" % (
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type(item_to_format),
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err
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)
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)
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def handle_instance(self, instance):
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"""Format and print the instance provided.
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:param instance:
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The instance retrieved from the API that needs to be formatted.
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:type instance:
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cratonclient.crud.Resource
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"""
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raise NotImplementedError(
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"A formatter plugin subclassed Formatter but did not implement"
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" the handle_instance method."
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)
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def handle_generator(self, generator):
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"""Format and print the instance provided.
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:param generator:
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The generator retrieved from the API whose items need to be
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formatted.
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"""
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raise NotImplementedError(
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"A formatter plugin subclassed Formatter but did not implement"
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" the handle_generator method."
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)
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