argparse:确定使用了哪个子解析器 [英] argparse: identify which subparser was used

问题描述

我认为这一定很容易，但我不明白.

I think this must be easy but I do not get it.

假设我有以下 arparse 解析器:

Assume I have the following arparse parser:

import argparse

parser = argparse.ArgumentParser( version='pyargparsetest 1.0' )
subparsers = parser.add_subparsers(help='commands')

# all
all_parser = subparsers.add_parser('all', help='process all apps')

# app
app_parser = subparsers.add_parser('app', help='process a single app')
app_parser.add_argument('appname', action='store', help='name of app to process')

如何识别使用了哪个子解析器?调用:

How can I identify, which subparser was used? calling:

print parser.parse_args(["all"])

给我一​​个空的命名空间:

gives me an empty namespace:

Namespace()

推荐答案

请参阅 quornian 的回答 这个问题比我的好，应该是公认的答案.

Please see quornian's answer to this question, which is better than mine and should be the accepted answer.

根据 argparse 文档 parser.parse_args(...) 将只包含主解析器和被选择的子解析器的属性".不幸的是，这可能不足以确定使用了哪个子解析器.文档建议使用 set_defaults(...) 子解析器上的方法来解决这个问题.

According to the argparse documentation the result of parser.parse_args(...) will "only contain attributes for the main parser and the sub parser that was selected". Unfortunately this may not be enough information to determine which sub parser was used. The documentation recommends using the set_defaults(...) method on the sub parser to solve this problem.

例如，我在您的代码中添加了对 set_defaults() 的调用:

For example, I've added calls to set_defaults() to your code:

import argparse

parser = argparse.ArgumentParser( version='pyargparsetest 1.0' )
subparsers = parser.add_subparsers(help='commands')

# all
all_parser = subparsers.add_parser('all', help='process all apps')
all_parser.set_defaults(which='all')

# app
app_parser = subparsers.add_parser('app', help='process a single app')
app_parser.add_argument('appname', action='store', help='name of app to process')
app_parser.set_defaults(which='app')

现在如果你跑

print parser.parse_args(["all"])

结果是

Namespace(which='all')

查看add_subparsers() 文档以获取更多信息和另一个示例.

Check out the add_subparsers() documentation for more information and another example.

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