使用argparse中的位置参数作为函数名 [英] Using positional arguments from argparse as function name

问题描述

我已经使用argparse设置了一个脚本，该脚本为我提供了以下命名空间:

I have set up a script with argparse that gives me the following NameSpace:

Namespace(action='list', input='all', target='domain')

我做了一些根据位置调用的函数，此刻我有了一种工作状态，可以用如下代码的代码来调用它们:

I have made a few functions which are called according to the positionals, and at the moment I have a working situation by calling them with blurbs of code like this one:

if args.action == 'list':
    if len(sys.argv) == 2:
        parser.print_help()
        sys.exit(0)
elif args.target == 'domain':
    domain_list()
elif args.target == 'forwarding':
    forwarding_list()
elif args.target == 'transport':
    transport_list()
elif args.target == 'user':
    user_list()
else:
    all_list()

我知道这可以做到，比这更好.但是由于我对Python的了解有限，我似乎无法弄清楚这一点.

I know this can be done way, way better than this; but with my limited knowledge of Python, I can't seem to figure this one out.

回顾:我想要的东西，如果可能的话(伪代码)

Recap: I want something like, if at all possible (pseudocode)

if args.action == 'add':
    target = args.target
    target_add()

其中target_add()类似于domain_add().

提前谢谢！

推荐答案

听起来操作可能是list或add，而target可能是domain，forwarding，transport或user.是的，如果您必须手动列出每个选项组合会执行的操作，则最终会得到很多if..then..else代码.

It sounds like action could be list or add, while target could be domain, forwarding, transport, or user. Yes, you would end up with a lot of if..then..else code if you had to manually list what each combination of options would do.

这里是一种简化方法:

• 使用itertools.product生成所有可能的组合 选项.
• 使用白名单调度字典将选项映射到函数.键是2元组，例如('domain','list')或('transport','add').这些值是关联的功能对象.

• Use itertools.product to generate all the possible combinations of options.
• Use a whitelist dispatch dict to map options to functions. The keys are 2-tuples, such as ('domain','list'), or ('transport','add'). The values are the associated function objects.

import itertools as IT

targets = 'domain forwarding transport user'.split()
actions = 'list add'.split()

dispatch = {key:globals()['%s_%s' % key] for key in IT.product(targets, actions)}

# This calls the function specified by (target, action).
# The `dict.get` method is used so that if the key is not in `dispatch`, the `all_list` function is called.
dispatch.get((args.target, args.action), all_list)()

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