Proposal for implementing frozendict in stdlib to cleanup implementing code that involves data mapping and conversions

python_ideas_frozendict.py

"""
Proposal for implementing frozendict in stdlib to cleanup implementing code
that involves data mapping and conversions.
"""

from types import MappingProxyType

#####################################################
# Current way
#####################################################
DEFAULT_FIELD_MAP = MappingProxyType({
    'a': 'A',
    'b': 'B'
})

DEFAULT_PARSER_MAP = MappingProxyType({
    'a': int,
    'b': str
})


def passthrough(v):
    return v


def convert(record, parsers=DEFAULT_PARSER_MAP, field_map=DEFAULT_FIELD_MAP,
            transformers=MappingProxyType(dict())):

    record = {k: parsers[k](v) for k, v in record.items()}
    record = {field_map.get(k, k): v for k, v in record.items()}
    record = {k: transformers.get(k, passthrough)(v) for k, v in record.items()}

    return record


def example_convert():
    record = {'a': '10', 'b': 'hello'}
    custom_transformers = {'B': str.upper}

    return convert(record, transformers=custom_transformers)


#####################################################
# Alternative way
#####################################################

# hypothetical for example
frozendict = dict

DEFAULT_FIELD_MAP = frozendict(a='A', b='B')
DEFAULT_PARSER_MAP = frozendict(a=int, b=str)


def frozen_convert(record, parsers=DEFAULT_PARSER_MAP, field_map=DEFAULT_FIELD_MAP,
                   transformers=frozendict()):
    record = {k: parsers[k](v) for k, v in record.items()}
    record = {field_map.get(k, k): v for k, v in record.items()}
    record = {k: transformers.get(k, passthrough)(v) for k, v in record.items()}

    return record


def example_frozen_convert():
    record = {'a': '10', 'b': 'hello'}
    custom_transformers = {'B': str.upper}

    return convert(record, transformers=custom_transformers)