Mapper.load() - Code Metrics - Inspection of "Rely on AttributeError, not falsiness" - jacebrowning/yorm - Measure and Improve Code Quality continuously with Scrutinizer

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by Jace

created 2017-01-06 20:55 UTC

Mapper.load() D

↳ Parent: Mapper

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	39
CRAP Score	11

Importance

Changes	2
Bugs	0	Features	0

Metric	Value
c	2
b	0
f	0
dl	0
loc	56
ccs	39
cts	39
cp	1
rs	4.4262
cc	11
crap	11

How to fix Long Method Complexity

"""Core object-file mapping functionality."""

import functools
from pprint import pformat
import logging

from . import common, diskutils, exceptions, types, settings
from .bases import Container

log = logging.getLogger(__name__)


def file_required(method):
    """Decorator for methods that require the file to exist."""

    @functools.wraps(method)
    def wrapped(self, *args, **kwargs):
        if self.deleted:
            msg = "File deleted: {}".format(self.path)
            raise exceptions.DeletedFileError(msg)
        elif self.missing and not settings.fake:
            msg = "File missing: {}".format(self.path)
            raise exceptions.MissingFileError(msg)
        else:
            return method(self, *args, **kwargs)

    return wrapped


def prevent_recursion(method):
    """Decorator to prevent indirect recursive calls."""

    @functools.wraps(method)
    def wrapped(self, *args, **kwargs):
        # pylint: disable=protected-access
        if self._activity:
            return
        self._activity = True
        result = method(self, *args, **kwargs)
        self._activity = False
        return result

    return wrapped


def prefix(obj):
    """Prefix a string with a fake designator if enabled."""
    fake = "(fake) " if settings.fake else ""
    name = obj if isinstance(obj, str) else "'{}'".format(obj)
    return fake + name


class Mapper:
    """Utility class to map an object's attributes to a file.

    To start mapping attributes to a file:

        create -> [empty] -> FILE

    When getting an attribute:

        FILE -> read -> [text] -> parse -> [dict] -> load -> ATTRIBUTES

    When setting an attribute:

        ATTRIBUTES -> save -> [dict] -> dump -> [text] -> write -> FILE

    After the mapped file is no longer needed:

        delete -> [null] -> FILE

    """

    def __init__(self, obj, path, attrs, *,
                 auto_create=True, auto_save=True, auto_track=False):
        self._obj = obj
        self.path = path
        self.attrs = attrs
        self.auto_create = auto_create
        self.auto_save = auto_save
        self.auto_track = auto_track

        self.exists = diskutils.exists(self.path)
        self.deleted = False
        self.auto_save_after_load = False

        self._activity = False
        self._timestamp = 0
        self._fake = ""

    def __str__(self):
        return str(self.path)

    @property
    def missing(self):
        return not self.exists

    @property
    def modified(self):
        """Determine if the file has been modified."""
        if settings.fake:
            changes = self._timestamp is not None
            return changes
        elif not self.exists:
            return True
        else:
            # TODO: this raises an exception is the file is missing
            was = self._timestamp
            now = diskutils.stamp(self.path)
            return was != now

    @modified.setter
    @file_required
    def modified(self, changes):
        """Mark the file as modified if there are changes."""
        if changes:
            log.debug("Marked %s as modified", prefix(self))
            self._timestamp = 0
        else:
            if settings.fake or self.path is None:
                self._timestamp = None
            else:
                self._timestamp = diskutils.stamp(self.path)
            log.debug("Marked %s as unmodified", prefix(self))

    @property
    def text(self):
        """Get file contents as a string."""
        log.info("Getting contents of %s...", prefix(self))
        if settings.fake:
            text = self._fake
        else:
            text = self._read()
        log.trace("Text read: \n%s", text[:-1])
        return text

    @text.setter
    def text(self, text):
        """Set file contents from a string."""
        log.info("Setting contents of %s...", prefix(self))
        if settings.fake:
            self._fake = text
        else:
            self._write(text)
        log.trace("Text wrote: \n%s", text.rstrip())
        self.modified = True

    @property
    def data(self):
        """Get the file values as a dictionary."""
        text = self._read()
        data = diskutils.parse(text, self.path)
        log.trace("Parsed data: \n%s", pformat(data))
        return data

    @data.setter
    def data(self, data):
        """Set the file values from a dictionary."""
        text = diskutils.dump(data, self.path)
        self._write(text)

    def create(self):
        """Create a new file for the object."""
        log.info("Creating %s for %r...", prefix(self), self._obj)
        if self.exists:
            log.warning("Already created: %s", self)
            return
        if not settings.fake:
            diskutils.touch(self.path)
        self.exists = True
        self.deleted = False

    @file_required
    @prevent_recursion
    def load(self):
        """Update the object's mapped attributes from its file."""
        log.info("Loading %r from %s...", self._obj, prefix(self))

        # Update all attributes
        attrs2 = self.attrs.copy()
        for name, data in self.data.items():
            attrs2.pop(name, None)

            # Find a matching converter
            try:
                converter = self.attrs[name]
            except KeyError:
                if self.auto_track:
                    converter = types.match(name, data)
                    self.attrs[name] = converter
                else:
                    msg = "Ignored unknown file attribute: %s = %r"
                    log.warning(msg, name, data)
                    continue

            # Convert the parsed value to the attribute's final type
            attr = getattr(self._obj, name, None)
            if isinstance(attr, converter) and \
                    issubclass(converter, Container):
                attr.update_value(data, auto_track=self.auto_track)
            else:
                log.trace("Converting attribute %r to %r", name, converter)
                attr = converter.to_value(data)
                setattr(self._obj, name, attr)
            self._remap(attr, self)
            log.trace("Value loaded: %s = %r", name, attr)

        # Add missing attributes
        for name, converter in attrs2.items():
            try:
                existing_attr = getattr(self._obj, name)
            except AttributeError:
                value = converter.create_default()
                msg = "Default value for missing object attribute: %s = %r"
                log.warning(msg, name, value)
                setattr(self._obj, name, value)
                self._remap(value, self)
            else:
                if issubclass(converter, Container) and \
                        not isinstance(existing_attr, converter):
                    msg = "Converting container attribute %r to %r"
                    log.trace(msg, name, converter)
                    value = converter.create_default()
                    setattr(self._obj, name, value)
                    self._remap(value, self)

        # Set meta attributes
        self.modified = False

    def _remap(self, obj, root):
        """Attach mapper on nested attributes."""
        if isinstance(obj, Container):
            common.set_mapper(obj, root)

            if isinstance(obj, dict):
                for obj2 in obj.values():
                    self._remap(obj2, root)
            else:
                assert isinstance(obj, list)
                for obj2 in obj:
                    self._remap(obj2, root)

    @file_required
    @prevent_recursion
    def save(self):
        """Format and save the object's mapped attributes to its file."""
        log.info("Saving %r to %s...", self._obj, prefix(self))

        # Format the data items
        data = self.attrs.__class__()
        for name, converter in self.attrs.items():
            try:
                value = getattr(self._obj, name)
            except AttributeError:
                data2 = converter.to_data(None)
                msg = "Default data for missing object attribute: %s = %r"
                log.warning(msg, name, data2)
            else:
                data2 = converter.to_data(value)

            log.trace("Data to save: %s = %r", name, data2)
            data[name] = data2

        # Save the formatted to disk
        self.data = data

        # Set meta attributes
        self.modified = True
        self.auto_save_after_load = self.auto_save

    def delete(self):
        """Delete the object's file from the file system."""
        if self.exists:
            log.info("Deleting %s...", prefix(self))
            diskutils.delete(self.path)
        else:
            log.warning("Already deleted: %s", self)
        self.exists = False
        self.deleted = True

    @file_required
    def _read(self):
        """Read text from the object's file."""
        if settings.fake:
            return self._fake
        elif not self.exists:
            return ""
        else:
            return diskutils.read(self.path)

    @file_required
    def _write(self, text):
        """Write text to the object's file."""
        if settings.fake:
            self._fake = text
        else:
            diskutils.write(text, self.path)


1		"""Core object-file mapping functionality."""
2
3	1	import functools
4	1	from pprint import pformat
5	1	import logging
6
7	1	from . import common, diskutils, exceptions, types, settings
8	1	from .bases import Container
9
10	1	log = logging.getLogger(__name__)
11
12
13	1	def file_required(method):
14		"""Decorator for methods that require the file to exist."""
15
16	1	@functools.wraps(method)
17		def wrapped(self, args, *kwargs):
18	1	if self.deleted:
19	1	msg = "File deleted: {}".format(self.path)
20	1	raise exceptions.DeletedFileError(msg)
21	1	elif self.missing and not settings.fake:
22	1	msg = "File missing: {}".format(self.path)
23	1	raise exceptions.MissingFileError(msg)
24		else:
25	1	return method(self, args, *kwargs)
26
27	1	return wrapped
28
29
30	1	def prevent_recursion(method):
31		"""Decorator to prevent indirect recursive calls."""
32
33	1	@functools.wraps(method)
34		def wrapped(self, args, *kwargs):
35		# pylint: disable=protected-access
36	1	if self._activity:
37	1	return
38	1	self._activity = True
39	1	result = method(self, args, *kwargs)
40	1	self._activity = False
41	1	return result
42
43	1	return wrapped
44
45
46	1	def prefix(obj):
47		"""Prefix a string with a fake designator if enabled."""
48	1	fake = "(fake) " if settings.fake else ""
49	1	name = obj if isinstance(obj, str) else "'{}'".format(obj)
50	1	return fake + name
51
52
53	1	class Mapper:
54		"""Utility class to map an object's attributes to a file.
55
56		To start mapping attributes to a file:
57
58		create -> [empty] -> FILE
59
60		When getting an attribute:
61
62		FILE -> read -> [text] -> parse -> [dict] -> load -> ATTRIBUTES
63
64		When setting an attribute:
65
66		ATTRIBUTES -> save -> [dict] -> dump -> [text] -> write -> FILE
67
68		After the mapped file is no longer needed:
69
70		delete -> [null] -> FILE
71
72		"""
73
74	1	def __init__(self, obj, path, attrs, *,
75		auto_create=True, auto_save=True, auto_track=False):
76	1	self._obj = obj
77	1	self.path = path
78	1	self.attrs = attrs
79	1	self.auto_create = auto_create
80	1	self.auto_save = auto_save
81	1	self.auto_track = auto_track
82
83	1	self.exists = diskutils.exists(self.path)
84	1	self.deleted = False
85	1	self.auto_save_after_load = False
86
87	1	self._activity = False
88	1	self._timestamp = 0
89	1	self._fake = ""
90
91	1	def __str__(self):
92	1	return str(self.path)
93
94	1	@property
95		def missing(self):
96	1	return not self.exists
97
98	1	@property
99		def modified(self):
100		"""Determine if the file has been modified."""
101	1	if settings.fake:
102	1	changes = self._timestamp is not None
103	1	return changes
104	1	elif not self.exists:
105	1	return True
106		else:
107		# TODO: this raises an exception is the file is missing
108	1	was = self._timestamp
109	1	now = diskutils.stamp(self.path)
110	1	return was != now
111
112	1	@modified.setter
113	1	@file_required
114		def modified(self, changes):
115		"""Mark the file as modified if there are changes."""
116	1	if changes:
117	1	log.debug("Marked %s as modified", prefix(self))
118	1	self._timestamp = 0
119		else:
120	1	if settings.fake or self.path is None:
121	1	self._timestamp = None
122		else:
123	1	self._timestamp = diskutils.stamp(self.path)
124	1	log.debug("Marked %s as unmodified", prefix(self))
125
126	1	@property
127		def text(self):
128		"""Get file contents as a string."""
129	1	log.info("Getting contents of %s...", prefix(self))
130	1	if settings.fake:
131	1	text = self._fake
132		else:
133	1	text = self._read()
134	1	log.trace("Text read: \n%s", text[:-1])
135	1	return text
136
137	1	@text.setter
138		def text(self, text):
139		"""Set file contents from a string."""
140	1	log.info("Setting contents of %s...", prefix(self))
141	1	if settings.fake:
142	1	self._fake = text
143		else:
144	1	self._write(text)
145	1	log.trace("Text wrote: \n%s", text.rstrip())
146	1	self.modified = True
147
148	1	@property
149		def data(self):
150		"""Get the file values as a dictionary."""
151	1	text = self._read()
152	1	data = diskutils.parse(text, self.path)
153	1	log.trace("Parsed data: \n%s", pformat(data))
154	1	return data
155
156	1	@data.setter
157		def data(self, data):
158		"""Set the file values from a dictionary."""
159	1	text = diskutils.dump(data, self.path)
160	1	self._write(text)
161
162	1	def create(self):
163		"""Create a new file for the object."""
164	1	log.info("Creating %s for %r...", prefix(self), self._obj)
165	1	if self.exists:
166	1	log.warning("Already created: %s", self)
167	1	return
168	1	if not settings.fake:
169	1	diskutils.touch(self.path)
170	1	self.exists = True
171	1	self.deleted = False
172
173	1	@file_required
174	1	@prevent_recursion
175		def load(self):
176		"""Update the object's mapped attributes from its file."""
177	1	log.info("Loading %r from %s...", self._obj, prefix(self))
178
179		# Update all attributes
180	1	attrs2 = self.attrs.copy()
181	1	for name, data in self.data.items():
182	1	attrs2.pop(name, None)
183
184		# Find a matching converter
185	1	try:
186	1	converter = self.attrs[name]
187	1	except KeyError:
188	1	if self.auto_track:
189	1	converter = types.match(name, data)
190	1	self.attrs[name] = converter
191		else:
192	1	msg = "Ignored unknown file attribute: %s = %r"
193	1	log.warning(msg, name, data)
194	1	continue
195
196		# Convert the parsed value to the attribute's final type
197	1	attr = getattr(self._obj, name, None)
198	1	if isinstance(attr, converter) and \
199		issubclass(converter, Container):
200	1	attr.update_value(data, auto_track=self.auto_track)
201		else:
202	1	log.trace("Converting attribute %r to %r", name, converter)
203	1	attr = converter.to_value(data)
204	1	setattr(self._obj, name, attr)
205	1	self._remap(attr, self)
206	1	log.trace("Value loaded: %s = %r", name, attr)
207
208		# Add missing attributes
209	1	for name, converter in attrs2.items():
210	1	try:
211	1	existing_attr = getattr(self._obj, name)
212	1	except AttributeError:
213	1	value = converter.create_default()
214	1	msg = "Default value for missing object attribute: %s = %r"
215	1	log.warning(msg, name, value)
216	1	setattr(self._obj, name, value)
217	1	self._remap(value, self)
218		else:
219	1	if issubclass(converter, Container) and \
220		not isinstance(existing_attr, converter):
221	1	msg = "Converting container attribute %r to %r"
222	1	log.trace(msg, name, converter)
223	1	value = converter.create_default()
224	1	setattr(self._obj, name, value)
225	1	self._remap(value, self)
226
227		# Set meta attributes
228	1	self.modified = False
229
230	1	def _remap(self, obj, root):
231		"""Attach mapper on nested attributes."""
232	1	if isinstance(obj, Container):
233	1	common.set_mapper(obj, root)
234
235	1	if isinstance(obj, dict):
236	1	for obj2 in obj.values():
237	1	self._remap(obj2, root)
238		else:
239	1	assert isinstance(obj, list)
240	1	for obj2 in obj:
241	1	self._remap(obj2, root)
242
243	1	@file_required
244	1	@prevent_recursion
245		def save(self):
246		"""Format and save the object's mapped attributes to its file."""
247	1	log.info("Saving %r to %s...", self._obj, prefix(self))
248
249		# Format the data items
250	1	data = self.attrs.__class__()
251	1	for name, converter in self.attrs.items():
252	1	try:
253	1	value = getattr(self._obj, name)
254	1	except AttributeError:
255	1	data2 = converter.to_data(None)
256	1	msg = "Default data for missing object attribute: %s = %r"
257	1	log.warning(msg, name, data2)
258		else:
259	1	data2 = converter.to_data(value)
260
261	1	log.trace("Data to save: %s = %r", name, data2)
262	1	data[name] = data2
263
264		# Save the formatted to disk
265	1	self.data = data
266
267		# Set meta attributes
268	1	self.modified = True
269	1	self.auto_save_after_load = self.auto_save
270
271	1	def delete(self):
272		"""Delete the object's file from the file system."""
273	1	if self.exists:
274	1	log.info("Deleting %s...", prefix(self))
275	1	diskutils.delete(self.path)
276		else:
277	1	log.warning("Already deleted: %s", self)
278	1	self.exists = False
279	1	self.deleted = True
280
281	1	@file_required
282		def _read(self):
283		"""Read text from the object's file."""
284	1	if settings.fake:
285	1	return self._fake
286	1	elif not self.exists:
287		return ""
288		else:
289	1	return diskutils.read(self.path)
290
291	1	@file_required
292		def _write(self, text):
293		"""Write text to the object's file."""
294	1	if settings.fake:
295	1	self._fake = text
296		else:
297		diskutils.write(text, self.path)
298

jacebrowning / yorm

Push — develop ( 42c0e7...a8ebf0 )

Mapper.load() D

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