一个函数，该函数创建以传入的参数命名的函数

cynic 发表于 Dev

犬儒

有没有一种方法可以使传入的变量在以后命名的其他函数中被调用呢？

对于这个例子，让我们假装https://example.com/engine_list返回该XML文件，当我把它在get_search_engine_xml

<engines>
    <engine address="https://www.google.com/">Google</engine>
    <engine address="https://www.bing.com/">Bing</engine>
    <engine address="https://duckduckgo.com/">DuckDuckGo</engine>
</engines>

这是我的代码：

import re
import requests
import xml.etree.ElementTree as ET
base_url = 'https://example.com'

def make_safe(s):
    s = re.sub(r"[^\w\s]", '', s)
    s = re.sub(r"\s+", '_', s)
    s = str(s)
    return s

# This is what I'm trying to figure out how to do correctly, create a function
# named after the engine returned in get_search_engine_xml(), to be called later
def create_get_engine_function(function_name, address):
    def function_name():
        r = requests.get(address)
    return function_name

def get_search_engine_xml():
    url = base_url + '/engine_list'
    r = requests.get(url)
    engines_list = str(r.content)
    engines_root = ET.fromstring(engines_list)
    for child in engines_root:
        engine_name = child.text.lower()
        engine_name = make_safe(engine_name)
        engine_address = child.attrib['address']
        create_get_engine_function(engine_name, engine_address)

## Runs without error.
get_search_engine_xml()

## But if I try to call one of the functions.
google()

我收到以下错误。

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'google' is not defined

当我注销时，定义engine_name和engine_address似乎可以正常工作。因此，我非常确定问题出在create_get_engine_function上，该函数当然不知道我在做什么，并且我试图将类似的问题拼凑在一起。

您可以使用传入的参数来命名另一个函数创建的函数吗？有一个更好的方法吗？

懒狗

您可以将它们分配给globals（）

def create_get_engine_function(function_name, address):
    def function():
        r = requests.get(address)

    function.__name__ = function_name
    function.__qualname__ = function_name  # for Python 3.3+ 
    globals()[function_name] = function

尽管，根据您实际要完成的工作，一个更好的设计是将所有引擎名称/地址存储在字典中，并根据需要访问它们：

# You should probably should rename this to 'parse_engines_from_xml'
def get_search_engine_xml(): 
    ...
    search_engines = {} # maps names to addresses
    for child in engines_root:
        ...
        search_engines[engine_name] = engine_address
    return search_engines

engines = get_search_engine_xml()

e = requests.get(engines['google'])
<do whatever>
e = requests.get(engines['bing'])
<do whatever>

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