boost程序选项短/长参数名称

问题描述

我已经实现了路由，以通过遍历 po :: variable_map 来打印出 boost :: program_options 对象中可用的所有选项以及它们的当前值

I have implemented a routing to print out all of the options that are available in my boost::program_options objects along with their current values by iterating over the po::variable_map.

这样，我可以直接打印选项的长名称及其值.但是，我不知道如何从长选项名中检索短选项名(即--help中的-h).有什么建议怎么做吗?

With this I can directly print the long name of the option along with its value. However, I do not know, how to retrieve the short option name from the long option name (i.e. -h from --help). Any suggestions how to do this?

推荐答案

我记得在最近的答案中描述了为什么 variable_map 太迟到"以至于无法了解选项描述:

I remember describing in a recent answer why variable_map is "too late" to know about the option descriptions:

• 助推器.方便的variables_map.利用在options_desctription
中指定类型的优势

• Boost. Handy variables_map. Taking advantage of having specified the type in the options_desctription

简而言之，variable_map位于存储组件，因此与选项描述"(位于选项说明组件).

In short, the variable_map sits in the Storage Component of the library and as such is isolated from the Option Descriptions (which lives in the Options Description Component).

您可以使用中间结果，即解析器组件:

You could work with the intermediate results, the raw output from the Parsers Component:

因此，让我们尝试在此处算出一个示例:

So, let's try to work out a sample here:

    po::parsed_options const intermediate = po::parse_command_line(ac, av, desc);

    //////////////////////////////////
    // print the extended usage info as per the question
    //
    for (auto& entry : intermediate.options)
    {
        po::option_description const& opt = desc.find(entry.string_key, false, false, false);

        std::cout << "\nActual tokens involved: ";
        for (auto& tok : entry.original_tokens)
            std::cout << "'" << tok << "' ";
        for (std::string const& v : entry.value)
            std::cout << "\nAssociated value: " << v;
        std::cout << "\n-----------------------------------------------------------\n";
        std::cout << "opt.format_name()        : "        << opt.format_name()                                      << "\n";
        std::cout << "opt.long_name()          : "        << opt.long_name()                                        << "\n";
        std::cout << "opt.canonical_display_name('-'): "  << opt.canonical_display_name(cls::allow_dash_for_short)  << "\n";
        std::cout << "opt.canonical_display_name('/'): "  << opt.canonical_display_name(cls::allow_slash_for_short) << "\n";
        std::cout << "opt.canonical_display_name('--'): " << opt.canonical_display_name(cls::allow_long)            << "\n";
    }

打印例如

Actual tokens involved: '-C' '42'
Associated value: 42
-----------------------------------------------------------
opt.format_name()        : -C [ --compression ]
opt.long_name()          : compression
opt.canonical_display_name('-'): -C
opt.canonical_display_name('/'): /C
opt.canonical_display_name('--'): --compression

Actual tokens involved: '--name' 'santa'
Associated value: santa
-----------------------------------------------------------
opt.format_name()        : -n [ --name ]
opt.long_name()          : name
opt.canonical_display_name('-'): -n
opt.canonical_display_name('/'): /n
opt.canonical_display_name('--'): --name
Compression level was set to 42.

#include <boost/program_options.hpp>
#include <boost/program_options/detail/parsers.hpp>
#include <iostream>

namespace po  = boost::program_options;
namespace cls = po::command_line_style;

int main(int ac, char** av) {
    // Declare the supported options.
    po::options_description desc("Allowed options");
    desc.add_options()
        ("help", "produce help message")
        ("name,n", po::value<std::string>(), "specify the name")
        ("compression,C", po::value<int>(), "set compression level")
        ;

    po::variables_map vm;
    po::parsed_options const intermediate = po::parse_command_line(ac, av, desc);

    //////////////////////////////////
    // print the extended usage info as per the question
    //
    for (auto& entry : intermediate.options)
    {
        po::option_description const& opt = desc.find(entry.string_key, false, false, false);

        std::cout << "\nActual tokens involved: ";
        for (auto& tok : entry.original_tokens)
            std::cout << "'" << tok << "' ";
        for (std::string const& v : entry.value)
            std::cout << "\nAssociated value: " << v;
        std::cout << "\n-----------------------------------------------------------\n";
        std::cout << "opt.format_name()        : "        << opt.format_name()                                      << "\n";
        std::cout << "opt.long_name()          : "        << opt.long_name()                                        << "\n";
        std::cout << "opt.canonical_display_name('-'): "  << opt.canonical_display_name(cls::allow_dash_for_short)  << "\n";
        std::cout << "opt.canonical_display_name('/'): "  << opt.canonical_display_name(cls::allow_slash_for_short) << "\n";
        std::cout << "opt.canonical_display_name('--'): " << opt.canonical_display_name(cls::allow_long)            << "\n";
    }

    //////////////////////////////////

    po::store(intermediate, vm);
    po::notify(vm);

    if (vm.count("help")) {
        std::cout << desc << "\n";
        return 1;
    }

    if (vm.count("compression")) {
        std::cout << "Compression level was set to "
            << vm["compression"].as<int>() << ".\n";
    } else {
        std::cout << "Compression level was not set.\n";
    }
}

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