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recursively convert nested dicts to nested namedtuples, giving you something like immutable object literals
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from UserDict import IterableUserDict | |
import collections | |
__author__ = 'github.com/hangtwenty' | |
def tupperware(mapping): | |
""" Convert mappings to 'tupperwares' recursively. | |
Lets you use dicts like they're JavaScript Object Literals (~=JSON)... | |
It recursively turns mappings (dictionaries) into namedtuples. | |
Thus, you can cheaply create an object whose attributes are accessible | |
by dotted notation (all the way down). | |
Use cases: | |
* Fake objects (useful for dependency injection when you're making | |
fakes/stubs that are simpler than proper mocks) | |
* Storing data (like fixtures) in a structured way, in Python code | |
(data whose initial definition reads nicely like JSON). You could do | |
this with dictionaries, but namedtuples are immutable, and their | |
dotted notation can be clearer in some contexts. | |
.. doctest:: | |
>>> t = tupperware({ | |
... 'foo': 'bar', | |
... 'baz': {'qux': 'quux'}, | |
... 'tito': { | |
... 'tata': 'tutu', | |
... 'totoro': 'tots', | |
... 'frobnicator': ['this', 'is', 'not', 'a', 'mapping'] | |
... } | |
... }) | |
>>> t # doctest: +ELLIPSIS | |
Tupperware(tito=Tupperware(...), foo='bar', baz=Tupperware(qux='quux')) | |
>>> t.tito # doctest: +ELLIPSIS | |
Tupperware(frobnicator=[...], tata='tutu', totoro='tots') | |
>>> t.tito.tata | |
'tutu' | |
>>> t.tito.frobnicator | |
['this', 'is', 'not', 'a', 'mapping'] | |
>>> t.foo | |
'bar' | |
>>> t.baz.qux | |
'quux' | |
Args: | |
mapping: An object that might be a mapping. If it's a mapping, convert | |
it (and all of its contents that are mappings) to namedtuples | |
(called 'Tupperwares'). | |
Returns: | |
A tupperware (a namedtuple (of namedtuples (of namedtuples (...)))). | |
If argument is not a mapping, it just returns it (this enables the | |
recursion). | |
""" | |
if (isinstance(mapping, collections.Mapping) and | |
not isinstance(mapping, ProtectedDict)): | |
for key, value in mapping.iteritems(): | |
mapping[key] = tupperware(value) | |
return namedtuple_from_mapping(mapping) | |
return mapping | |
def namedtuple_from_mapping(mapping, name="Tupperware"): | |
this_namedtuple_maker = collections.namedtuple(name, mapping.iterkeys()) | |
return this_namedtuple_maker(**mapping) | |
class ProtectedDict(IterableUserDict): | |
""" A class that exists just to tell `tupperware` not to eat it. | |
`tupperware` eats all dicts you give it, recursively; but what if you | |
actually want a dictionary in there? This will stop it. Just do | |
ProtectedDict({...}) or ProtectedDict(kwarg=foo). | |
""" | |
def tupperware_from_kwargs(**kwargs): | |
return tupperware(kwargs) |
@brennv You did really great job. Appreciated
Thanks for this work!
I was searching for the same, I required it on 3.6, so in case that somebody else requires it here is (basically I just update some references):
from collections import UserDict
import collections
__author__ = 'github.com/hangtwenty'
def tupperware(mapping):
""" Convert mappings to 'tupperwares' recursively.
Lets you use dicts like they're JavaScript Object Literals (~=JSON)...
It recursively turns mappings (dictionaries) into namedtuples.
Thus, you can cheaply create an object whose attributes are accessible
by dotted notation (all the way down).
Use cases:
* Fake objects (useful for dependency injection when you're making
fakes/stubs that are simpler than proper mocks)
* Storing data (like fixtures) in a structured way, in Python code
(data whose initial definition reads nicely like JSON). You could do
this with dictionaries, but namedtuples are immutable, and their
dotted notation can be clearer in some contexts.
.. doctest::
>>> t = tupperware({
... 'foo': 'bar',
... 'baz': {'qux': 'quux'},
... 'tito': {
... 'tata': 'tutu',
... 'totoro': 'tots',
... 'frobnicator': ['this', 'is', 'not', 'a', 'mapping']
... }
... })
>>> t # doctest: +ELLIPSIS
Tupperware(tito=Tupperware(...), foo='bar', baz=Tupperware(qux='quux'))
>>> t.tito # doctest: +ELLIPSIS
Tupperware(frobnicator=[...], tata='tutu', totoro='tots')
>>> t.tito.tata
'tutu'
>>> t.tito.frobnicator
['this', 'is', 'not', 'a', 'mapping']
>>> t.foo
'bar'
>>> t.baz.qux
'quux'
Args:
mapping: An object that might be a mapping. If it's a mapping, convert
it (and all of its contents that are mappings) to namedtuples
(called 'Tupperwares').
Returns:
A tupperware (a namedtuple (of namedtuples (of namedtuples (...)))).
If argument is not a mapping, it just returns it (this enables the
recursion).
"""
if (isinstance(mapping, collections.Mapping) and
not isinstance(mapping, ProtectedDict)):
for key, value in mapping.items():
mapping[key] = tupperware(value)
return namedtuple_from_mapping(mapping)
return mapping
def namedtuple_from_mapping(mapping, name="Tupperware"):
this_namedtuple_maker = collections.namedtuple(name, mapping.keys())
return this_namedtuple_maker(**mapping)
class ProtectedDict(UserDict):
""" A class that exists just to tell `tupperware` not to eat it.
`tupperware` eats all dicts you give it, recursively; but what if you
actually want a dictionary in there? This will stop it. Just do
ProtectedDict({...}) or ProtectedDict(kwarg=foo).
"""
def tupperware_from_kwargs(**kwargs):
return tupperware(kwargs)
Again @hangtwenty, thanks!
Thanks. I am searching for it too. From stackoverflow, copy and paste it here.
def tupleware(obj):
if isinstance(obj, dict):
fields = sorted(obj.keys())
namedtuple_type = namedtuple(
typename='TWare',
field_names=fields,
rename=True,
)
field_value_pairs = OrderedDict(
(str(field), tupleware(obj[field])) for field in fields)
try:
return namedtuple_type(**field_value_pairs)
except TypeError:
# Cannot create namedtuple instance so fallback to dict (invalid attribute names)
return dict(**field_value_pairs)
elif isinstance(obj, (list, set, tuple, frozenset)):
return [tupleware(item) for item in obj]
else:
return obj
Great. very usefull. thanks!
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Is there anyway to specify "parent" to point to one level above?