module NumRu

Index

class NumRu::Misc::KeywordOpt

Overview

A class to facilitate optional keyword arguments. More specifically, it helps the use of a Hash to mimic the keyword argument system. With this, you can set default values and description to each keyword argument.

Classes defined supplementarilly

class NumRu::Misc::HelpMessagingException < StandardError

This is for your convenience. See the usage example below.

Usage example

Suppose that you introduce keyword arguments “flag” and “number” to the method “hoge” in a class/module Foo. It can be done as follows:

require 'numru/misc'  # or, specifically, require 'numru/misc/keywordopt'
include NumRu

class Foo
  @@opt_hoge = Misc::KeywordOpt.new(
    ['flag',   false, 'whether or not ...'],
    ['number', 1,     'number of ...'],
    ['help',   false, 'show help message']
  )
  def hoge(regular_arg1, regular_arg2, options=nil)
    opt = @@opt_hoge.interpret(options)
    if opt['help']
      puts @@opt_hoge.help
      puts ' Current values='+opt.inspect
      raise Misc::HelpMessagingException, '** show help message and raise **'
    end
    # do what you want below 
    # (options are set in the Hash opt: opt['flag'] and opt['number'])
  end
end

Here, the options are defined in the class variable @@opt_hoge with option names, default values, and descriptions (for help messaging). One can use the method hoge as follows:

foo = Foo.new
...
x = ...
y = ...
...
foo.hoge( x, y, {'flag'=>true, 'number'=>10} )

Or equivalently,

foo.hoge( x, y, 'flag'=>true, 'number'=>10 )

because '{}' can be omitted here.

Tails of options names can be shortened as long as unambiguous:

foo.hoge( x, y, 'fla'=>true, 'num'=>10 )

To show the help message, call

foo.hoge( x, y, 'help'=>true )

This will cause the following help message printed with the exception HelpMessagingException raised.

<< Description of options >>
 option name => default value   description:
  "flag" =>     false   whether or not ...
  "number" =>   1       number of ...
  "help" =>     false   show help message
Current values={"help"=>true, "number"=>1, "flag"=>false}
NumRu::Misc::HelpMessagingException: ** help messaging done **
       from (irb):78:in "hoge"
       from (irb):83

Do not affraid to write long descriptions. The help method

breaks lines nicely if they are long.

Class methods

module NumRu::Misc::MD_Iterators

A Mixin. To be included in a class with multi-dimension indexing support (such as NArray).

Index

Methods