The parse_args function

The parse_args function

parse_args([args,] settings; as_symbols::Bool = false)

This is the central function of the ArgParse module. It takes a Vector of arguments and an ArgParseSettings object, and returns a Dict{String,Any}. If args is not provided, the global variable ARGS will be used.

When the keyword argument as_symbols is true, the function will return a Dict{Symbol,Any} instead.

The returned Dict keys are defined (possibly implicitly) in settings, and their associated values are parsed from args. Special keys are used for more advanced purposes; at the moment, one such key exists: %COMMAND% (_COMMAND_ when using as_symbols=true; see the Commands section).

Arguments are parsed in sequence and matched against the argument table in settings to determine whether they are long options, short options, option arguments or positional arguments:

  • long options begin with a double dash "--"; if a '=' character is found, the remainder is the option argument; therefore, ["--opt=arg"] and ["--opt", "arg"] are equivalent if --opt takes at least one argument. Long options can be abbreviated (e.g. --opt instead of --option) as long as there is no ambiguity.
  • short options begin with a single dash "-" and their name consists of a single character; they can be grouped together (e.g. ["-x", "-y"] can become ["-xy"]), but in that case only the last option in the group can take an argument (which can also be grouped, e.g. ["-a", "-f", "file.txt"] can be passed as ["-affile.txt"] if -a does not take an argument and -f does). The '=' character can be used to separate option names from option arguments as well (e.g. -af=file.txt).
  • positional arguments are anything else; they can appear anywhere.

The special string "--" can be used to signal the end of all options; after that, everything is considered as a positional argument (e.g. if args = ["--opt1", "--", "--opt2"], the parser will recognize --opt1 as a long option without argument, and --opt2 as a positional argument).

The special string "-" is always parsed as a positional argument.

The parsing can stop early if a :show_help or :show_version action is triggered, or if a parsing error is found.

Some ambiguities can arise in parsing, see the Parsing details section for a detailed description of how they're solved.