1from itertools import chain, starmap
  2from statistics import mean
  3
  4
  5class AddByVolumeMixin:
  6    """Allow adding isntances by their volume."""
  7
  8    __radd__ = lambda self, other: self.volume + getattr(other, 'volume', other)
  9
 10
 11class Material(AddByVolumeMixin):
 12    """Represent a material."""
 13
 14    def __init__(self, mass):
 15        self.mass = mass
 16        self.obsolete = False
 17
 18    def use(self):
 19        """Ensure not used so far and make obsolete."""
 20        assert not self.obsolete and not setattr(self, 'obsolete', True)
 21
 22    @property
 23    def volume(self):
 24        """Get volume of an instance."""
 25        return self.mass / self.density
 26
 27    @property
 28    def primitive_cls_names(self):
 29        """Get list of primitive class names used by this instance's class."""
 30        return self.__class__.__name__.split('_')
 31
 32
 33class Factory(AddByVolumeMixin):
 34    """Factory that generates materials."""
 35
 36    _factories = []  # All Factory instances
 37    _classes = {}  # All known material types behind their name as str
 38
 39    def __init__(self):
 40        self._factories.append(self)
 41        self._products = []
 42
 43    @staticmethod
 44    def _store_output(fun):
 45        """Store objects getting out for future reference."""
 46        def decorated(self, *args, **kwargs):
 47            result = fun(self, *args, **kwargs)
 48            self._products.extend(result if type(result) is tuple else [result])
 49            return result
 50        return decorated
 51
 52    @_store_output
 53    def __call__(self, *args, **kwargs):
 54        """Create new materials."""
 55        if not bool(args) ^ bool(kwargs):
 56            raise ValueError
 57        if kwargs:
 58            return tuple(self._from_classnames(**kwargs))
 59        [obj.use() for obj in args]  # Make materials obsolete
 60
 61        return self._from_products(*args)
 62
 63    @staticmethod
 64    def _objs_prims(objects):
 65        """Get a sorted list of all promitives' names from a list of objects."""
 66        return sorted(chain(*map(lambda obj: obj.primitive_cls_names, objects)))
 67
 68    def _from_classnames(self, **kwargs):
 69        """Create materials from classnames (instance called with kwargs)."""
 70        if not set(kwargs.keys()).issubset(set(self._classes)):
 71            raise ValueError
 72        yield from (self._classes[name](mass) for name, mass in kwargs.items())
 73
 74    def _from_products(self, *args):
 75        """Create materials from instances (instance called with args)."""
 76        cls = self.generate_material_class('_'.join(self._objs_prims(args)))
 77        return cls(sum(map(lambda obj: obj.mass, args)))
 78
 79    @classmethod
 80    def generate_material_class(cls, name, density=None):
 81        """Generate a new class if not existing, else return existing."""
 82        if name not in cls._classes:
 83            prims = map(cls._classes.__getitem__, name.split('_'))
 84            density = density or mean(map(lambda obj: obj.density, prims))
 85            cls._classes[name] = type(name, (Material,), {'density': density})
 86        return cls._classes[name]
 87
 88    @property
 89    def volume(self):
 90        """Volume generated by this factory."""
 91        return sum(filter(lambda prd: not prd.obsolete, self._products))
 92
 93    @classmethod
 94    def can_build_together(cls, volume):
 95        """Whether can build a wall from all factories' volume."""
 96        return sum(cls._factories) >= volume
 97
 98    def can_build(self, volume):
 99        """Whether can build a wall from this factory's volume."""
100        return self.volume >= volume
101
102
103_PRIMITIVES = {'Concrete': 2500, 'Brick': 2000,
104               'Stone': 1600, 'Wood': 600, 'Steel': 7700}
105Concrete, Brick, Stone, Wood, Steel = starmap(Factory.generate_material_class,
106                                              _PRIMITIVES.items())