python实现一个通用的插件类
本文提供了一种插件类的实现方案。定义插件管理器
插件管理器用于注册、销毁、执行插件。
import abc
from functools import wraps
from typing import Callable, Dict
from pydantic import (
BaseModel,
validate_arguments,
ValidationError as PydanticValidationError,
)
def import_string(dotted_path: str) -> Callable:
"""Import a dotted module path and return the attribute/class designated by the
last name in the path. Raise ImportError if the import failed.
Args:
dotted_path: 字符串表示的模块类，module.class
Returns:
返回加载的模块中的对象
"""
try:
module_path, class_name = dotted_path.rsplit(".", 1)
except ValueError:
raise ImportError("{} doesn't look like a module path".format(dotted_path))
module: ModuleType = import_module(module_path)
try:
# 返回模块中的类
return getattr(module, class_name)
except AttributeError:
raise ImportError(
'Module "{}" does not define a "{}" attribute/class'.format(
module_path, class_name
)
)
class FunctionsManager:
"""函数管理器 ."""
# 存放注册的可执行对象
__hub = {}# type: ignore
@classmethod
def register_invocation_cls(cls, invocation_cls: InvocationMeta, name=None) -> None:
if not name:
func_name = invocation_cls.Meta.func_name
else:
func_name = name
if not isinstance(func_name, str):
raise ValueError(f"func_name {func_name} should be string")
existed_invocation_cls = cls.__hub.get(func_name)
if existed_invocation_cls:
raise RuntimeError(
"func register error, {}'s func_name {} conflict with {}".format(
existed_invocation_cls, func_name, invocation_cls
)
)
# 存放类的实例
cls.__hub = invocation_cls()
@classmethod
def register_funcs(cls, func_dict) -> None:
for func_name, func_obj in func_dict.items():
if not isinstance(func_name, str):
raise ValueError(f"func_name {func_name} should be string")
if func_name in cls.__hub:
raise ValueError(
"func register error, {}'s func_name {} conflict with {}".format(
func_obj, func_name, cls.__hub
)
)
if isinstance(func_obj, str):
func = import_string(func_obj)
elif isinstance(func_obj, Callable):
func = func_obj
else:
raise ValueError(
"func register error, {} is not be callable".format(
func_obj, func_name
)
)
cls.__hub = func
@classmethod
def clear(cls) -> None:
"""清空注册信息 ."""
cls.__hub = {}
@classmethod
def all_funcs(cls) -> Dict:
"""获得所有的注册信息. """
return cls.__hub
@classmethod
def get_func(cls, func_name: str) -> Callable:
"""获得注册的函数 ."""
func_obj = cls.__hub.get(func_name)
if not func_obj:
raise ValueError("func object {} not found".format(func_name))
return func_obj
@classmethod
def func_call(cls, func_name: str, *args, **kwargs):
"""根据函数名执行注册的函数 ."""
func = cls.get_func(func_name)
return func(*args, **kwargs)
定义元类
派生的类可自行注册到插件管理器。
class InvocationMeta(type):
"""
Metaclass for function invocation
"""
def __new__(cls, name, bases, dct):
# ensure initialization is only performed for subclasses of Plugin
parents =
if not parents:
return super().__new__(cls, name, bases, dct)
new_cls = super().__new__(cls, name, bases, dct)
# meta validation
meta_obj = getattr(new_cls, "Meta", None)
if not meta_obj:
raise AttributeError("Meta class is required")
func_name = getattr(meta_obj, "func_name", None)
if not func_name:
raise AttributeError("func_name is required in Meta")
desc = getattr(meta_obj, "desc", None)
if desc is not None and not isinstance(desc, str):
raise AttributeError("desc in Meta should be str")
# register func
FunctionsManager.register_invocation_cls(new_cls)
return new_cls
定义元类的一个抽象派生类
支持参数验证。
class BaseInvocation(metaclass=InvocationMeta):
"""
Base class for function invocation
"""
class Inputs(BaseModel):
"""
输入校验器
"""
pass
@validate_arguments# type: ignore
def __call__(self, *args, **kwargs):
# 输入参数校验, 仅可能是 args 或 kwargs 之一
try:
params = {}
if args:
inputs_meta = getattr(self.Inputs, "Meta", None)
inputs_ordering = getattr(inputs_meta, "ordering", None)
if isinstance(inputs_ordering, list):
if len(args) > len(inputs_ordering):
raise Exception(f"Too many arguments for inputs: {args}")
params = dict(zip(inputs_ordering, args))
elif kwargs:
params = kwargs
# 参数校验
if params:
self.Inputs(**params)
except PydanticValidationError as e:
raise Exception(e)
# 执行自定义业务逻辑
return self.invoke(*args, **kwargs)
@abc.abstractmethod
def invoke(self, *args, **kwargs):
"""自定义业务逻辑 ."""
raise NotImplementedError()
定义装饰器
def register_class(name: str):
def _register_class(cls: BaseInvocation):
FunctionsManager.register_invocation_cls(cls, name=name)
@wraps(cls)
def wrapper():
return cls()
return wrapper
return _register_class
def register_func(name: str):
def _register_func(func: Callable):
FunctionsManager.register_funcs({name: func})
@wraps(func)
def wrapper(*args, **kwargs):
return func(*args, **kwargs)
return wrapper
return _register_func
单元测试
from pydantic import BaseModel
from .register import FunctionsManager, register_func, register_class, BaseInvocation
@register_func("add")
def add(x: int, y: int) -> int:
return x + y
class Add(BaseInvocation):
class Meta:
func_name = "multiply"
class Inputs(BaseModel):
"""
输入校验器
"""
x: int
y: int
class Meta:
ordering = ["x", "y"]
def invoke(self, x: int, y: int) -> int:
return x * y
@register_class("subtract")
class Subtract:
class Inputs(BaseModel):
"""
输入校验器
"""
x: int
y: int
class Meta:
ordering = ["x", "y"]
def __call__(self, x: int, y: int) -> int:
return x - y
class TestFunctionsManager:
def test_register_func(self):
func = FunctionsManager.get_func("add")
assert func(2, 3) == 5
def test_register_class(self):
func = FunctionsManager.get_func("subtract")
assert func(2, 3) == -1
def test_metaclass(self):
func = FunctionsManager.get_func("multiply")
assert func(2, 3) == 6
参考
https://github.com/TencentBlueKing/bkflow-feel/blob/main/bkflow_feel/utils.py
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