def smart_getter(obj, strict=False):
'''Returns a smart getter for `obj`.
If `obj` is a mapping, it returns the ``.get()`` method bound to the
object `obj`, otherwise it returns a partial of ``getattr`` on `obj`.
:param strict: Set this to True so that the returned getter checks that
keys/attrs exists. If `strict` is True the getter may
raise a KeyError or an AttributeError.
.. versionchanged:: 1.5.3 Added the parameter `strict`.
'''
from .types import is_mapping
if is_mapping(obj):
if not strict:
return obj.get
else:
def _get(key, default=Unset):
try:
return obj[key]
except KeyError:
if default is Unset:
raise
else:
return default
return _get
else:
if not strict:
return lambda attr, default=None: getattr(obj, attr, default)
else:
def _partial(attr, default=Unset):
try:
return getattr(obj, attr)
except AttributeError:
if default is Unset:
raise
else:
return default
return _partial
def smart_copy(*args, **kwargs):
'''Copies the first apparition of attributes (or keys) from `sources` to
`target`.
:param sources: The objects from which to extract keys or attributes.
:param target: The object to fill.
:param defaults: Default values for the attributes to be copied as
explained below. Defaults to False.
:type defaults: Either a bool, a dictionary, an iterable or a callable.
Every `sources` and `target` are always positional arguments. There should
be at least one source. `target` will always be the last positional
argument.
If `defaults` is a dictionary or an iterable then only the names provided
by itering over `defaults` will be copied. If `defaults` is a dictionary,
and one of its key is not found in any of the `sources`, then the value of
the key in the dictionary is copied to `target` unless:
- It's the value :class:`xoutil.types.Required` or an instance of Required.
- An exception object
- A sequence with is first value being a subclass of Exception. In which
case :class:`xoutil.data.adapt_exception` is used.
In these cases a KeyError is raised if the key is not found in the
sources.
If `default` is an iterable and a key is not found in any of the sources,
None is copied to `target`.
If `defaults` is a callable then it should receive one positional
arguments for the current `attribute name` and several keyword arguments
(we pass ``source``) and return either True or False if the attribute
should be copied.
If `defaults` is False (or None) only the attributes that do not start
with a "_" are copied, if it's True all attributes are copied.
When `target` is not a mapping only valid Python identifiers will be
copied.
Each `source` is considered a mapping if it's an instance of
`collections.Mapping` or a `MappingProxyType`.
The `target` is considered a mapping if it's an instance of
`collections.MutableMapping`.
:returns: `target`.
.. versionchanged:: 1.7.0 `defaults` is now keyword only.
'''
from collections import MutableMapping
from xoutil.types import is_collection, is_mapping, Required
from xoutil.data import adapt_exception
from xoutil.validators.identifiers import is_valid_identifier
defaults = kwargs.pop('defaults', False)
if kwargs:
raise TypeError('smart_copy does not accept a "%s" keyword argument'
% kwargs.keys()[0])
sources, target = args[:-1], args[-1]
if not sources:
raise TypeError('smart_copy requires at least one source')
if isinstance(target, (bool, type(None), int, float, str_base)):
raise TypeError('target should be a mutable object, not %s' %
type(target))
if isinstance(target, MutableMapping):
def setter(key, val):
target[key] = val
else:
def setter(key, val):
if is_valid_identifier(key):
setattr(target, key, val)
_mapping = is_mapping(defaults)
if _mapping or is_collection(defaults):
for key, val in ((key, get_first_of(sources, key, default=Unset))
for key in defaults):
if val is Unset:
if _mapping:
val = defaults.get(key, None)
else:
val = None
exc = adapt_exception(val, key=key)
if exc or val is Required or isinstance(val, Required):
raise KeyError(key)
setter(key, val)
else:
keys = []
for source in sources:
get = smart_getter(source)
if is_mapping(source):
items = (name for name in source)
else:
items = dir(source)
for key in items:
private = isinstance(key, str_base) and key.startswith('_')
if (defaults is False or defaults is None) and private:
copy = False
elif callable(defaults):
copy = defaults(key, source=source)
else:
copy = True
if key not in keys:
keys.append(key)
if copy:
setter(key, get(key))
return target
