caikit.core.modules.meta

This module contains an implementation of a metaclass that hijacks all ${class}.load(…) invocations.

For a good read on metaclasses, see https://realpython.com/python-metaclasses/

Our goal is to have every instance of a caikit.core.ModuleBase automatically populated with metadata when it is constructed, without requiring anything of the module authors. The source of this metadata will be the config.yml file that resides within the module directory to be loaded. Since we require the path to that file in order to read the model’s metadata, we cannot simply define a base constructor. Instead, we patch over the module’s .load() function, which is guaranteed to be called with a path to a serialized module.

Additionally, the naive solution of manually patching .load functions does not work when inheritance is involved. For example:

import caikit.core

class ParentModule(caikit.core.ModuleBase):

    @classmethod
    def load(cls, module_path):
        return cls()

class ChildModule(ParentModule):

    @classmethod
    def load(cls, module_path):
        return super().load()

# This is fine!
assert isinstance(ChildModule.load(), ChildModule)

def injector(load_fn):
    def injected_load(*args):
        module = load_fn(*args)
        module.metadata = {"stuff"}
        return module
    return classmethod(injected_load)

for clz in (ParentModule, ChildModule):
    # But this line binds the new load function directly to each class :(
    clz.load = injector(clz.load)

# And this will now raise since ParentModule is returned
assert isinstance(ChildModule.load(), ChildModule)

Instead of binding new metadata-injecting load functions directly to a class at import time, we need to bind the new load function at contruction time, when the class hierarchy with inheritance is known.

Attributes

log
error

Classes

_ModuleBaseMeta

This is the metaclass used by caikit.core.ModuleBase.

Module Contents

caikit.core.modules.meta.log

caikit.core.modules.meta.error

class caikit.core.modules.meta._ModuleBaseMeta

Bases: abc.ABCMeta

This is the metaclass used by caikit.core.ModuleBase.

This metaclass populates the metadata property of any module that is created by invoking a load classmethod on a derived class.

property tasks: List[caikit.core.TaskBase]

__setattr__(name, val)

Overwrite __setattr__ to warn on any dynamic updates to the load function. We’d rather not lose all the work we did to wrap .load with metadata injection in the constructor!