Dear SeqAn users, supporters, and subscribers,

We are thrilled to announce the first Sharg parser release: 1.0.0 with most of the API being stable.

We have outsourced the SeqAn3 Argument Parser to its own light-weight, dependency-free repository: The Sharg parser.

Most of the API stayed similar. We added a new, flexible config design for adding options and flags, improving readability and maintainability. Not unexpectedly, we have some changes in namespace and naming:

The former seqan3::argument_parser is now the sharg::parser

If you have any trouble porting your code from SeqAn3 to the Sharg parser, please donโ€™t hesitate to reach out to us on GitHub or Gitter!

  • Get to know the Sharg parser with our tutorials.
  • Visit our API documentation.
  • Check out our Sharg Cookbook. It contains a listing of code examples on how to perform particular tasks using the library.

While we will present essential changes compared to the seqan3::argument_parser in this message, you can also find a comprehensive list of the changes in our changelog.


:tada: New Features

The new sharg::config design

An option flag or positional option is added with only two parameters:

  1. A value that stores the command line parameter (nothing changed here)
  2. A sharg::config object (NEW)


parser.add_option(val, 'i', "int", "some int");


parser.add_option(val, sharg::config{.short_id = 'i', 
                                     .long_id = "int", 
                                     .description = "some int"});

Although it is a little longer, it is easier to understand, more flexible and future-proof.

We take advantage of Designated initializers. E.g., you can leave out parameters you donโ€™t need, but beware that the order must be as specified in sharg::config.

You can now set an option as required without the need of the sharg::option_spec

parser.add_option(val, sharg::config{.short_id = 'i', .required = true});

Alter the default message

You can now alter the default message printed on the help page. E.g.

int i{};
parser.add_option(val, sharg::config{.short_id = 'i', .default_message = "Calculated from your data"});

Instead of Default: 0., it prints

    -i (signed 32 bit integer)
    Default: Calculated from your data.

:hammer_and_wrench: Notable API changes

Name changes

If you are switching from the seqan3::argument_parser to the sharg::parser, there are several name changes. All of them can be fixed with a simple search & replace:

  • The namespace of all entities is now sharg instead of seqan3
  • Every occurrence of argument_parser has been replaced with parser
  • The concept seqan::parser_compatible_option has been renamed to sharg::parsable

The new sharg::config design

The new config design is also an API break because we do not support the former calls from the seqan3::argument_parser.

We removed the sharg::option_spec as it is obsolete in the new API.


To avoid being dependent on the SeqAn3 I/O module, you now have to give a list of file extensions explicitly to sharg::input_file_validator and sharg::output_file_validator:

sharg::input_file_validator validator{std::vector<std::string>{{"exe"}, {"fasta"}}};

Please follow the SeqAn3 issue to see how the file extensions can be extracted from SeqAn3 files.

:electric_plug: Tooling

  • Sharg 1.0.0 is known to compile with GCC 10.4, 11.3, and 12.2. Future versions might work, but were not yet available at the time of this release.
  • Other compilers, e.g., clang, and MSVC, have not been tested yet with Sharg 1.0.0.
  • We use doxygen 1.9.4 to build our documentation.