【python】动态创建函数的一些方法

1、使用lambda函数

# 匿名函数， 返回值为函数
func = lambda: "foo"
print(func)

 

2、使用内部函数(局部函数)

# 类似装饰器写法
def decorator(func):
    def _(*args, **kwargs):
        return func(*args, **kwargs)
    return _

 

3、使用types.FunctionType创建

import types


def foo():
    return "foo"

func = types.FunctionType(foo.__code__, {})
print(func())

 

4、使用eval

foo = eval('lambda: "foo"')
print(foo)

 

5、使用AST

首先了解

https://docs.python.org/zh-cn/3.8/library/ast.html

import ast
import types
import codegen

from ast import *

import astunparse as astunparse
# 格式化展示AST Node


function_ast = FunctionDef(
    name='func',
    args=arguments(posonlyargs=[], args=[], vararg=None, kwonlyargs=[], kw_defaults=[], kwarg=None, defaults=[]),
    body=[Return(value=Str(s='hello world', lineno=1, col_offset=0), lineno=1, col_offset=0)],
    decorator_list=[],
    lineno=1,
    col_offset=0
)


module_ast = Module(body=[function_ast], type_ignores=[])
module_code = compile(module_ast, "<>", "exec")
function_code = [c for c in module_code.co_consts if isinstance(c, types.CodeType)][0]
func = types.FunctionType(function_code, {})
print(func())
# 格式化展示AST Node
print(astunparse.dump(module_ast))
# 展示定时的源码
print(codegen.to_source(module_ast))

输出：

hello world
Module(
  body=[FunctionDef(
    name='func',
    args=arguments(
      posonlyargs=[],
      args=[],
      vararg=None,
      kwonlyargs=[],
      kw_defaults=[],
      kwarg=None,
      defaults=[]),
    body=[Return(value=Constant(value='hello world'))],
    decorator_list=[])],
  type_ignores=[])
def func():
    return 'hello world'

 

 

参考链接：

https://www.cnblogs.com/olivetree123/p/5067685.html

https://www.cnblogs.com/LaoYuanPython/p/11087716.html

https://blog.csdn.net/ThinkTimes/article/details/110831176

https://blog.csdn.net/cunchi4221/article/details/107475657

https://github.com/journaldev/journaldev/tree/master/Python-3/basic_examples/

https://www.ghcc.net/node/3331829

https://docs.python.org/zh-cn/3.8/library/ast.html

https://pycoders-weekly-chinese.readthedocs.io/en/latest/issue3/static-modification-of-python-with-python-the-ast-module.html#

https://greentreesnakes.readthedocs.io/en/latest/nodes.html#function-and-class-definitions

https://www.csdn.net/tags/MtTaMg4sMjc5NzQ3LWJsb2cO0O0O.html

https://www.codenong.com/768634/