senf::console::kw Namespace Reference
[Supported command types]

Keyword argument tags. More...

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Detailed Description

Keyword argument tags.

The tags defined in this namespace are used as keyword arguments via the Boost.Parameter library.

For the keyword tags, the standard C++ scoping rules apply

namespace fty=senf::console::factory;

// Either qualify them with their complete namespace
dir.add(..., fty::Command(...)
    .arg( senf::console::kw::name = "name" ) );

// Or use a namespace alias
namespace kw = senf::console::kw;
dir.add(..., fty::Command(...)
    .arg( kw::name = "name" ) );

// Or import the keywords into the current namespace (beware of name collisions)
using namespace senf::console::kw;
dir.add(..., fty::Command(...)
    .arg( name = "name" ) );

The second alternative is preferred, the using namespace directive may be used as long as the keyword names do not clash with another visible symbol.

Argument attribute values

The keywords are used to set argument attributes. The keywords default_value and parser influence, how an argument is parsed/interpreted whereas name, description, type_name and default_doc are used to change the arguments documentation:

void command(int);

dir.add("command", fty::Command(&command)
    .arg( kw::name          = "name",
          kw::description   = "description",
          kw::default_value = 1,
          kw::type_name     = "type_name",
          kw::default_doc   = "default_doc" ) );

Will create the following documentation:

Usage:
    command [name:type_name]

With:
    name      description
        default: default_doc

See also:

senf::console::ParsedArgumentAttributor::arg()

Variables
unspecified_keyword_type	name
	Argument name.
unspecified_keyword_type	description
	One-line argument description.
unspecified_keyword_type	default_value
	Argument default value.
unspecified_keyword_type	type_name
	Type name of this arguments type.
unspecified_keyword_type	default_doc
	String rep of default value.
unspecified_keyword_type	parser
	Argument parser.

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Variable Documentation

unspecified_keyword_type senf::console::kw::
default_doc

String rep of default value.

By default, the default value is documented by converting the value to it's string representation using the corresponding return value formatter which by default uses boost::lexical_cast / iostreams. The displayed value can be changed by setting this attribute.

Definition at line 372 of file ParsedCommand.hh.

unspecified_keyword_type senf::console::kw::
default_value

Argument default value.

If a default value is specified for an argument, that argument is optional. If an overload is called with fewer arguments than defined, optional values will be used beginning at the last optional argument and going forward until all arguments have values assigned. E.g., an overload with 5 parameters a - e with two defaults attached:

command a:int [b:int] c:int [d:int] e:int

When calling the overload, the arguments will be assigned in the following way:

command 1 2	SyntaxErrorException: invalid number of arguments
command 1 2 3	a = 1	b = default	c = 2	d = default	e = 3
command 1 2 3 4	a = 1	b = 2	c = 3	d = default	e = 4
command 1 2 3 4 5	a = 1	b = 2	c = 3	d = 4	e = 5
command 1 2 3 4 5 6	SyntaxErrorException: invalid number of arguments

So, if you use default values as you are used to, assigning default values to consecutive trailing arguments, they work like they do in C++ and most other languages

Definition at line 326 of file ParsedCommand.hh.

unspecified_keyword_type senf::console::kw::
description

One-line argument description.

This description is shown in the argument reference. If several overloads have same-named arguments, only one of them should be documented. This documentation then applies to all arguments of that name.

Definition at line 320 of file ParsedCommand.hh.

unspecified_keyword_type senf::console::kw::
name

Argument name.

Sets the displayed name of the argument.

Definition at line 318 of file ParsedCommand.hh.

unspecified_keyword_type senf::console::kw::
parser

Argument parser.

The argument parser is used to convert the argument token list returned by the console/config parser into the appropriate value. If not set explicitly, this conversion is supplied by the ArgumentTraits class.

Setting the parser attribute allows to use a custom parser. The parser is an arbitrary callable object with the signature

void parser(senf::console::ParseCommandInfo::TokensRange const & tokens, value_type & out);

where value_type is the type of the overload parameter. The parser must read and parse the complete tokens range and return the parsed value in out. If the parser fails, it must raise a senf::console::SyntaxErrorException.

Definition at line 379 of file ParsedCommand.hh.

unspecified_keyword_type senf::console::kw::
type_name

Type name of this arguments type.

By default, the type of an argument is extracted from the C++ type name by taking the last component of the fully scoped name. This value can be changed by setting this attribute.

Definition at line 367 of file ParsedCommand.hh.