seqan3::custom::argument_parsing< t > Struct Template Reference

A type that can be specialised to provide customisation point implementations for the seqan3::argument_parser such that third party types may be adapted. More...

#include <seqan3/argument_parser/auxiliary.hpp>

Detailed Descriptionno-api

template<typename t>
struct seqan3::custom::argument_parsing< t >

A type that can be specialised to provide customisation point implementations for the seqan3::argument_parser such that third party types may be adapted.

Template Parameters

t	The type you wish to specialise for.

Named Enumerations

In order to use a third party type within the seqan3::argument_parser::add_option or seqan3::argument_parser::add_positional_option call, you can specialise this struct in the following way:

// SPDX-FileCopyrightText: 2006-2025 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2025 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: CC0-1.0
 
#include <ranges>
#include <system_error>
 
#include <seqan3/argument_parser/all.hpp>
 
namespace seqan3::custom
{
// Specialise the seqan3::custom::argument_parsing data structure to enable parsing of std::errc.
template <>
struct argument_parsing<std::errc>
{
    // Specialise a mapping from an identifying string to the respective value of your type Foo.
    static inline std::unordered_map<std::string_view, std::errc> const enumeration_names{
        {"no_error", std::errc{}},
        {"timed_out", std::errc::timed_out},
        {"invalid_argument", std::errc::invalid_argument},
        {"io_error", std::errc::io_error}};
};
 
} // namespace seqan3::custom
 
int main(int argc, char const * argv[])
{
    std::errc value{};
 
    seqan3::argument_parser parser{"my_program", argc, argv};
 
    // Because of the argument_parsing struct and
    // the static member function enumeration_names
    // you can now add an option that takes a value of type std::errc:
    parser.add_option(value,
                      'e',
                      "errc",
                      "Give me a std::errc value.",
                      seqan3::option_spec::standard,
                      seqan3::value_list_validator{(seqan3::enumeration_names<std::errc> | std::views::values)});
 
    try
    {
        parser.parse();
    }
    catch (seqan3::argument_parser_error const & ext) // the user did something wrong
    {
        std::cerr << "[PARSER ERROR] " << ext.what() << "\n"; // customize your error message
        return -1;
    }
 
    return 0;
}

Please note that by default the t const, t & and t const & specialisations of this class inherit the specialisation for t so you usually only need to provide a specialisation for t.

Note

Only use this if you cannot provide respective functions in your namespace. See the tutorial Parsing command line arguments with Sharg for an example of customising a type within your own namespace.

Remarks

For a complete overview, take a look at Argument Parser

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The documentation for this struct was generated from the following file:

• auxiliary.hpp