argparse:确定使用哪个子解析器 [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? 打电话:

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

编辑:请参阅 quornian的答案这个问题，比我的要好，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(...)的结果将仅包含属性用于主解析器和选定的子解析器".不幸的是，这可能不是足够的信息来确定使用了哪个子解析器.该文档建议在子解析器上使用 set_defaults(...) 方法解决这个问题.

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，我已将对set_defaults()的调用添加到您的代码中:

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，如果您运行

print parser.parse_args(["all"])

结果是

Namespace(which='all')

查看 add_subparsers() 文档以获取更多信息还有另一个例子.

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

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