Internal use. An implementation of Eratosthenes’ sieve

Raised when an unknown conversion error occurs.

Generated when trying to lookup a gem to indicate that the gem was found, but that it isn’t usable on the current platform.

fetch and install read these and report them to the user to aid in figuring out why a gem couldn’t be installed.

Utility module to define eRuby script as instance method.

Example

example.rhtml:

<% for item in @items %>
<b><%= item %></b>
<% end %>

example.rb:

require 'erb'
class MyClass
  extend ERB::DefMethod
  def_erb_method('render()', 'example.rhtml')
  def initialize(items)
    @items = items
  end
end
print MyClass.new([10,20,30]).render()

result:

<b>10</b>

<b>20</b>

<b>30</b>

HTTPAuth provides both basic and digest authentication.

To enable authentication for requests in WEBrick you will need a user database and an authenticator. To start, here’s an Htpasswd database for use with a DigestAuth authenticator:

config = { :Realm => 'DigestAuth example realm' }

htpasswd = WEBrick::HTTPAuth::Htpasswd.new 'my_password_file'
htpasswd.auth_type = WEBrick::HTTPAuth::DigestAuth
htpasswd.set_passwd config[:Realm], 'username', 'password'
htpasswd.flush

The :Realm is used to provide different access to different groups across several resources on a server. Typically you’ll need only one realm for a server.

This database can be used to create an authenticator:

config[:UserDB] = htpasswd

digest_auth = WEBrick::HTTPAuth::DigestAuth.new config

To authenticate a request call authenticate with a request and response object in a servlet:

def do_GET req, res
  @authenticator.authenticate req, res
end

For digest authentication the authenticator must not be created every request, it must be passed in as an option via WEBrick::HTTPServer#mount.

Numeric is the class from which all higher-level numeric classes should inherit.

Numeric allows instantiation of heap-allocated objects. Other core numeric classes such as Integer are implemented as immediates, which means that each Integer is a single immutable object which is always passed by value.

a = 1
1.object_id == a.object_id   #=> true

There can only ever be one instance of the integer 1, for example. Ruby ensures this by preventing instantiation. If duplication is attempted, the same instance is returned.

Integer.new(1)                   #=> NoMethodError: undefined method `new' for Integer:Class
1.dup                            #=> 1
1.object_id == 1.dup.object_id   #=> true

For this reason, Numeric should be used when defining other numeric classes.

Classes which inherit from Numeric must implement coerce, which returns a two-member Array containing an object that has been coerced into an instance of the new class and self (see coerce).

Inheriting classes should also implement arithmetic operator methods (+, -, * and /) and the <=> operator (see Comparable). These methods may rely on coerce to ensure interoperability with instances of other numeric classes.

class Tally < Numeric
  def initialize(string)
    @string = string
  end

  def to_s
    @string
  end

  def to_i
    @string.size
  end

  def coerce(other)
    [self.class.new('|' * other.to_i), self]
  end

  def <=>(other)
    to_i <=> other.to_i
  end

  def +(other)
    self.class.new('|' * (to_i + other.to_i))
  end

  def -(other)
    self.class.new('|' * (to_i - other.to_i))
  end

  def *(other)
    self.class.new('|' * (to_i * other.to_i))
  end

  def /(other)
    self.class.new('|' * (to_i / other.to_i))
  end
end

tally = Tally.new('||')
puts tally * 2            #=> "||||"
puts tally > 1            #=> true

Float objects represent inexact real numbers using the native architecture’s double-precision floating point representation.

Floating point has a different arithmetic and is an inexact number. So you should know its esoteric system. See following:

• docs.sun.com/source/806-3568/ncg_goldberg.html

• github.com/rdp/ruby_tutorials_core/wiki/Ruby-Talk-FAQ#floats_imprecise

• en.wikipedia.org/wiki/Floating_point#Accuracy_problems

Continuation objects are generated by Kernel#callcc, after having +require+d continuation. They hold a return address and execution context, allowing a nonlocal return to the end of the callcc block from anywhere within a program. Continuations are somewhat analogous to a structured version of C’s setjmp/longjmp (although they contain more state, so you might consider them closer to threads).

For instance:

require "continuation"
arr = [ "Freddie", "Herbie", "Ron", "Max", "Ringo" ]
callcc{|cc| $cc = cc}
puts(message = arr.shift)
$cc.call unless message =~ /Max/

produces:

Freddie
Herbie
Ron
Max

Also you can call callcc in other methods:

require "continuation"

def g
  arr = [ "Freddie", "Herbie", "Ron", "Max", "Ringo" ]
  cc = callcc { |cc| cc }
  puts arr.shift
  return cc, arr.size
end

def f
  c, size = g
  c.call(c) if size > 1
end

f

This (somewhat contrived) example allows the inner loop to abandon processing early:

require "continuation"
callcc {|cont|
  for i in 0..4
    print "#{i}: "
    for j in i*5...(i+1)*5
      cont.call() if j == 17
      printf "%3d", j
    end
  end
}
puts

produces:

0:   0  1  2  3  4
1:   5  6  7  8  9
2:  10 11 12 13 14
3:  15 16

Raised to stop the iteration, in particular by Enumerator#next. It is rescued by Kernel#loop.

loop do
  puts "Hello"
  raise StopIteration
  puts "World"
end
puts "Done!"

produces:

Hello
Done!

Raised by exit to initiate the termination of the script.

fatal is an Exception that is raised when Ruby has encountered a fatal error and must exit.

Raised when a signal is received.

begin
  Process.kill('HUP',Process.pid)
  sleep # wait for receiver to handle signal sent by Process.kill
rescue SignalException => e
  puts "received Exception #{e}"
end

produces:

received Exception SIGHUP

Raised when the arguments are wrong and there isn’t a more specific Exception class.

Ex: passing the wrong number of arguments

[1, 2, 3].first(4, 5)

raises the exception:

ArgumentError: wrong number of arguments (given 2, expected 1)

Ex: passing an argument that is not acceptable:

[1, 2, 3].first(-4)

raises the exception:

ArgumentError: negative array size

Raised when a feature is not implemented on the current platform. For example, methods depending on the fsync or fork system calls may raise this exception if the underlying operating system or Ruby runtime does not support them.

Note that if fork raises a NotImplementedError, then respond_to?(:fork) returns false.

A generic error class raised when an invalid operation is attempted. Kernel#raise will raise a RuntimeError if no Exception class is specified.

raise "ouch"

raises the exception:

RuntimeError: ouch

Raised when memory allocation fails.

date and datetime class - Tadayoshi Funaba 1998-2011

‘date’ provides two classes: Date and DateTime.

Terms and Definitions

Some terms and definitions are based on ISO 8601 and JIS X 0301.

Calendar Date

The calendar date is a particular day of a calendar year, identified by its ordinal number within a calendar month within that year.

In those classes, this is so-called “civil”.

Ordinal Date

The ordinal date is a particular day of a calendar year identified by its ordinal number within the year.

In those classes, this is so-called “ordinal”.

Week Date

The week date is a date identified by calendar week and day numbers.

The calendar week is a seven day period within a calendar year, starting on a Monday and identified by its ordinal number within the year; the first calendar week of the year is the one that includes the first Thursday of that year. In the Gregorian calendar, this is equivalent to the week which includes January 4.

In those classes, this is so-called “commercial”.

Julian Day Number

The Julian day number is in elapsed days since noon (Greenwich Mean Time) on January 1, 4713 BCE (in the Julian calendar).

In this document, the astronomical Julian day number is the same as the original Julian day number. And the chronological Julian day number is a variation of the Julian day number. Its days begin at midnight on local time.

In this document, when the term “Julian day number” simply appears, it just refers to “chronological Julian day number”, not the original.

In those classes, those are so-called “ajd” and “jd”.

Modified Julian Day Number

The modified Julian day number is in elapsed days since midnight (Coordinated Universal Time) on November 17, 1858 CE (in the Gregorian calendar).

In this document, the astronomical modified Julian day number is the same as the original modified Julian day number. And the chronological modified Julian day number is a variation of the modified Julian day number. Its days begin at midnight on local time.

In this document, when the term “modified Julian day number” simply appears, it just refers to “chronological modified Julian day number”, not the original.

In those classes, those are so-called “amjd” and “mjd”.

Date

A subclass of Object that includes the Comparable module and easily handles date.

A Date object is created with Date::new, Date::jd, Date::ordinal, Date::commercial, Date::parse, Date::strptime, Date::today, Time#to_date, etc.

require 'date'

Date.new(2001,2,3)
 #=> #<Date: 2001-02-03 ...>
Date.jd(2451944)
 #=> #<Date: 2001-02-03 ...>
Date.ordinal(2001,34)
 #=> #<Date: 2001-02-03 ...>
Date.commercial(2001,5,6)
 #=> #<Date: 2001-02-03 ...>
Date.parse('2001-02-03')
 #=> #<Date: 2001-02-03 ...>
Date.strptime('03-02-2001', '%d-%m-%Y')
 #=> #<Date: 2001-02-03 ...>
Time.new(2001,2,3).to_date
 #=> #<Date: 2001-02-03 ...>

All date objects are immutable; hence cannot modify themselves.

The concept of a date object can be represented as a tuple of the day count, the offset and the day of calendar reform.

The day count denotes the absolute position of a temporal dimension. The offset is relative adjustment, which determines decoded local time with the day count. The day of calendar reform denotes the start day of the new style. The old style of the West is the Julian calendar which was adopted by Caesar. The new style is the Gregorian calendar, which is the current civil calendar of many countries.

The day count is virtually the astronomical Julian day number. The offset in this class is usually zero, and cannot be specified directly.

A Date object can be created with an optional argument, the day of calendar reform as a Julian day number, which should be 2298874 to 2426355 or negative/positive infinity. The default value is Date::ITALY (2299161=1582-10-15). See also sample/cal.rb.

$ ruby sample/cal.rb -c it 10 1582
    October 1582
 S  M Tu  W Th  F  S
    1  2  3  4 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31

$ ruby sample/cal.rb -c gb  9 1752
   September 1752
 S  M Tu  W Th  F  S
       1  2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30

A Date object has various methods. See each reference.

d = Date.parse('3rd Feb 2001')
                             #=> #<Date: 2001-02-03 ...>
d.year                       #=> 2001
d.mon                        #=> 2
d.mday                       #=> 3
d.wday                       #=> 6
d += 1                       #=> #<Date: 2001-02-04 ...>
d.strftime('%a %d %b %Y')    #=> "Sun 04 Feb 2001"

Time is an abstraction of dates and times. Time is stored internally as the number of seconds with fraction since the Epoch, January 1, 1970 00:00 UTC. Also see the library module Date. The Time class treats GMT (Greenwich Mean Time) and UTC (Coordinated Universal Time) as equivalent. GMT is the older way of referring to these baseline times but persists in the names of calls on POSIX systems.

All times may have fraction. Be aware of this fact when comparing times with each other – times that are apparently equal when displayed may be different when compared.

Since Ruby 1.9.2, Time implementation uses a signed 63 bit integer, Bignum or Rational. The integer is a number of nanoseconds since the Epoch which can represent 1823-11-12 to 2116-02-20. When Bignum or Rational is used (before 1823, after 2116, under nanosecond), Time works slower as when integer is used.

Examples

All of these examples were done using the EST timezone which is GMT-5.

Creating a new Time instance

You can create a new instance of Time with Time::new. This will use the current system time. Time::now is an alias for this. You can also pass parts of the time to Time::new such as year, month, minute, etc. When you want to construct a time this way you must pass at least a year. If you pass the year with nothing else time will default to January 1 of that year at 00:00:00 with the current system timezone. Here are some examples:

Time.new(2002)         #=> 2002-01-01 00:00:00 -0500
Time.new(2002, 10)     #=> 2002-10-01 00:00:00 -0500
Time.new(2002, 10, 31) #=> 2002-10-31 00:00:00 -0500

You can pass a UTC offset:

Time.new(2002, 10, 31, 2, 2, 2, "+02:00") #=> 2002-10-31 02:02:02 +0200

Or a timezone object:

tz = timezone("Europe/Athens") # Eastern European Time, UTC+2
Time.new(2002, 10, 31, 2, 2, 2, tz) #=> 2002-10-31 02:02:02 +0200

You can also use Time::gm, Time::local and Time::utc to infer GMT, local and UTC timezones instead of using the current system setting.

You can also create a new time using Time::at which takes the number of seconds (or fraction of seconds) since the Unix Epoch.

Time.at(628232400) #=> 1989-11-28 00:00:00 -0500

Working with an instance of Time

Once you have an instance of Time there is a multitude of things you can do with it. Below are some examples. For all of the following examples, we will work on the assumption that you have done the following:

t = Time.new(1993, 02, 24, 12, 0, 0, "+09:00")

Was that a monday?

t.monday? #=> false

What year was that again?

t.year #=> 1993

Was it daylight savings at the time?

t.dst? #=> false

What’s the day a year later?

t + (60*60*24*365) #=> 1994-02-24 12:00:00 +0900

How many seconds was that since the Unix Epoch?

t.to_i #=> 730522800

You can also do standard functions like compare two times.

t1 = Time.new(2010)
t2 = Time.new(2011)

t1 == t2 #=> false
t1 == t1 #=> true
t1 <  t2 #=> true
t1 >  t2 #=> false

Time.new(2010,10,31).between?(t1, t2) #=> true

Timezone argument

A timezone argument must have local_to_utc and utc_to_local methods, and may have name, abbr, and dst? methods.

The local_to_utc method should convert a Time-like object from the timezone to UTC, and utc_to_local is the opposite. The result also should be a Time or Time-like object (not necessary to be the same class). The zone of the result is just ignored. Time-like argument to these methods is similar to a Time object in UTC without sub-second; it has attribute readers for the parts, e.g. year, month, and so on, and epoch time readers, to_i. The sub-second attributes are fixed as 0, and utc_offset, zone, isdst, and their aliases are same as a Time object in UTC. Also to_time, +, and - methods are defined.

The name method is used for marshaling. If this method is not defined on a timezone object, Time objects using that timezone object can not be dumped by Marshal.

The abbr method is used by ‘%Z’ in strftime.

The dst? method is called with a Time value and should return whether the Time value is in daylight savings time in the zone.

Auto conversion to Timezone

At loading marshaled data, a timezone name will be converted to a timezone object by find_timezone class method, if the method is defined.

Similarly, that class method will be called when a timezone argument does not have the necessary methods mentioned above.

Exception class used to return errors from the dbm library.