Class: ArgParser::KeywordArgument

Inherits:

ValueArgument

• Object
• Argument
• ValueArgument
• ArgParser::KeywordArgument

Defined in:

lib/arg-parser/argument.rb

Overview

An argument that is specified via a keyword prefix; typically used for optional arguments, although Keyword arguments can also be used for mandatory arguments where there is no natural ordering of arguments.

Instance Attribute Summary

• #value_optional ⇒ Object (also: #value_optional?)

  Whether the keyword argument must be specified with a non-missing value.

Attributes inherited from ValueArgument

#sensitive, #usage_value, #validation

Attributes inherited from Argument

#default, #description, #key, #on_parse, #required, #short_key, #usage_break

Instance Method Summary

• #initialize(key, desc, opts = {}, &block) ⇒ KeywordArgument constructor

  Creates a KeywordArgument, which is an argument that must be specified on a command-line using either a long form key (i.e. –key), or optionally, a short-form key (i.e. -k) should one be defined for this argument.

• #to_s ⇒ Object
• #to_use ⇒ Object

Methods inherited from Argument

lookup, register, to_key

Constructor Details

#initialize(key, desc, opts = {}, &block) ⇒ KeywordArgument

Creates a KeywordArgument, which is an argument that must be specified on a command-line using either a long form key (i.e. –key), or optionally, a short-form key (i.e. -k) should one be defined for this argument.

Parameters:

• key (Symbol) —

  the key that will be used to identify this argument value in the parse results.

• desc (String) —

  the description of this argument, displayed in the generated help screen.

• opts (Hash) (defaults to: {}) —

  a hash of options that govern the behaviour of this argument.

Options Hash (opts):

• :required (Boolean) —

  whether the keyword argument is a required argument that must appear in the command-line. Defaults to false.

• :value_optional (Boolean) —

  whether the keyword argument can be specified without a value. For example, a keyword argument might be used both as a flag, and to override a default value. Specifying the argument without a value would signify that the option is set, but the default value for the option should be used. Defaults to false (keyword argument cannot be specified without a value).

# File 'lib/arg-parser/argument.rb', line 377

def initialize(key, desc, opts = {}, &block)
    super
    @required = opts.fetch(:required, false)
    @value_optional = opts.fetch(:value_optional, false)
end

Instance Attribute Details

#value_optional ⇒ Object Also known as: value_optional?

Whether the keyword argument must be specified with a non-missing value. The default is false, meaning the keyword argument must be specified together with a value. When this property is set to a non-falsy value (i.e. not nil or false), the keyword argument can be specified either with or without a value (or not at all):

• If specified with a value, the value will be returned.

• If specified without a value, the value of this property will be returned.

• If not specified at all, the default value will be returned.

Returns:

• (Object) —

  If truthy, the argument does not require a value. If the argument is specified but no value is provided, the value of this property will be the argument value.

# File 'lib/arg-parser/argument.rb', line 354

def value_optional
  @value_optional
end

Instance Method Details

#to_s ⇒ Object

# File 'lib/arg-parser/argument.rb', line 383

def to_s
    "--#{key}".gsub('_', '-')
end

#to_use ⇒ Object

# File 'lib/arg-parser/argument.rb', line 387

def to_use
    sk = short_key ? "-#{short_key}, " : ''
    uv = value_optional ? "[#{usage_value}]" : usage_value
    "#{sk}#{self.to_s} #{uv}"
end