A little example that demonstrates how far you can push metaclasses insanity in Python.

magic.py

from functools import partial

from query import run_query


class QueryResolver(dict):
    def __getitem__(self, key):
        if key.lower().startswith('select_') and key not in self:
            self[key] = partial(run_query, key)
        return super().__getitem__(key)


class QueryProvider(type):
    @classmethod
    def __prepare__(cls, name, bases):
        return QueryResolver()

query.py

import re


def run_query(query, iterable, **kwargs):
    fields = list(get_fields(query))
    for element in iterable:
        if any(element[key] != value for key, value in kwargs.items()):
            continue

        if len(fields) > 1:
            yield {name if alias is None else alias: element[name]
                   for name, alias in fields}
        else:
            yield element[fields[0][0]]


def get_fields(query):
    for field in re.split(r'select_|_and_|_from', query, flags=re.I):
        if '_as_' in field.lower():
            yield re.split(r'_as_', field, maxsplit=1, flags=re.I)
        elif field:
            yield field, None

usage.py

from magic import QueryProvider


people = [
    {
        'name': 'Foo',
        'age': 36,
        'birthday': 'feb 3',
        'gender': 'girl'
    },
    {
        'name': 'Bar',
        'age': 19,
        'birthday': 'nov 14',
        'gender': 'boy'
    },
    {
        'name': 'Spam',
        'age': 48,
        'birthday': 'apr 26',
        'gender': 'girl'
    },
    {
        'name': 'Egg',
        'age': 36,
        'birthday': 'feb 3',
        'gender': 'boy'
    }
]


class WeirdContext(metaclass=QueryProvider):
    for person in select_name_and_birthday_as_date_of_birth_from(people, age=36):
        print(person)

    for boy, girl in zip(select_name_from(people, gender='boy'),
                         select_name_from(people, gender='girl')):
        print(boy, girl)