Python metaclass with support for per-class specialization via an index method.
Adds a __param__ field to classes programmatically so that you can store a
static field on them without having to define a new class and without having to
use a new name.
from indexed_meta import IndexedMetaclass # Base type but either will work fine
from indexed_meta import IndexedClass # Convenience type. Fixes repr(), str()
class Vec(IndexedClass):
def show(self):
# This is the value-add for this library. Use __param__ as you see fit.
# It is different per specialized class but the exact same when param is
# the same: Vec[1] == Vec[1]; Vec[1] != Vec[2]
print(self.__param__)
v1 = Vec[3]()
v1.show() # Prints `3`
Vec[1], Vec[2], Vec[3], Vec[1, 2, 3], Vec[frozenset([1, 2, 3])]
# It's possible to override the default __param__ of None by inheriting from a
# specialized class:
class Vec(metaclass=IndexedMetaclass):
...
class Vec4(Vec[4]):
...
assert Vec4.__param__ == 4 # Normally it would be `None`