No one is claiming exec-ing generated source code is the best way to implement something (namedtuple in this case). The correct way is to use metaclass, but as

No one is claiming exec-ing generated source code is the best way to implement something (namedtuple in this case). The correct way is to use metaclass, but as I noted in another comment exec-ing source code provides a significant speed up to using metaclasses. I imagine that was the rationale behind this particular namedtuple implementation.