Raised when attempting to convert special float values (in particular Infinity
or NaN
) to numerical classes which don’t support them.
Float::INFINITY.to_r #=> FloatDomainError: Infinity
Provides mathematical functions.
Example:
require "bigdecimal/math" include BigMath a = BigDecimal((PI(100)/2).to_s) puts sin(a,100) # => 0.99999999999999999999......e0
The Benchmark
module provides methods to measure and report the time used to execute Ruby code.
Measure the time to construct the string given by the expression "a"*1_000_000_000
:
require 'benchmark' puts Benchmark.measure { "a"*1_000_000_000 }
On my machine (OSX 10.8.3 on i5 1.7 GHz) this generates:
0.350000 0.400000 0.750000 ( 0.835234)
This report shows the user CPU time, system CPU time, the sum of the user and system CPU times, and the elapsed real time. The unit of time is seconds.
Do some experiments sequentially using the bm
method:
require 'benchmark' n = 5000000 Benchmark.bm do |x| x.report { for i in 1..n; a = "1"; end } x.report { n.times do ; a = "1"; end } x.report { 1.upto(n) do ; a = "1"; end } end
The result:
user system total real 1.010000 0.000000 1.010000 ( 1.014479) 1.000000 0.000000 1.000000 ( 0.998261) 0.980000 0.000000 0.980000 ( 0.981335)
Continuing the previous example, put a label in each report:
require 'benchmark' n = 5000000 Benchmark.bm(7) do |x| x.report("for:") { for i in 1..n; a = "1"; end } x.report("times:") { n.times do ; a = "1"; end } x.report("upto:") { 1.upto(n) do ; a = "1"; end } end
The result:
user system total real for: 1.010000 0.000000 1.010000 ( 1.015688) times: 1.000000 0.000000 1.000000 ( 1.003611) upto: 1.030000 0.000000 1.030000 ( 1.028098)
The times for some benchmarks depend on the order in which items are run. These differences are due to the cost of memory allocation and garbage collection. To avoid these discrepancies, the bmbm
method is provided. For example, to compare ways to sort an array of floats:
require 'benchmark' array = (1..1000000).map { rand } Benchmark.bmbm do |x| x.report("sort!") { array.dup.sort! } x.report("sort") { array.dup.sort } end
The result:
Rehearsal ----------------------------------------- sort! 1.490000 0.010000 1.500000 ( 1.490520) sort 1.460000 0.000000 1.460000 ( 1.463025) -------------------------------- total: 2.960000sec user system total real sort! 1.460000 0.000000 1.460000 ( 1.460465) sort 1.450000 0.010000 1.460000 ( 1.448327)
Report statistics of sequential experiments with unique labels, using the benchmark
method:
require 'benchmark' include Benchmark # we need the CAPTION and FORMAT constants n = 5000000 Benchmark.benchmark(CAPTION, 7, FORMAT, ">total:", ">avg:") do |x| tf = x.report("for:") { for i in 1..n; a = "1"; end } tt = x.report("times:") { n.times do ; a = "1"; end } tu = x.report("upto:") { 1.upto(n) do ; a = "1"; end } [tf+tt+tu, (tf+tt+tu)/3] end
The result:
user system total real for: 0.950000 0.000000 0.950000 ( 0.952039) times: 0.980000 0.000000 0.980000 ( 0.984938) upto: 0.950000 0.000000 0.950000 ( 0.946787) >total: 2.880000 0.000000 2.880000 ( 2.883764) >avg: 0.960000 0.000000 0.960000 ( 0.961255)
mkmf.rb is used by Ruby C extensions to generate a Makefile which will correctly compile and link the C extension to Ruby and a third-party library.
The Math
module contains module functions for basic trigonometric and transcendental functions. See class Float
for a list of constants that define Ruby’s floating point accuracy.
Domains and codomains are given only for real (not complex) numbers.
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.
Raised when a gem dependencies file specifies a ruby version that does not match the current version.
Individual switch class. Not important to the user.
Defined within Switch
are several Switch-derived classes: NoArgument
, RequiredArgument
, etc.
The command manager registers and installs all the individual sub-commands supported by the gem command.
Extra commands can be provided by writing a rubygems_plugin.rb file in an installed gem. You should register your command against the Gem::CommandManager
instance, like this:
# file rubygems_plugin.rb require 'rubygems/command_manager' Gem::CommandManager.instance.register_command :edit
You should put the implementation of your command in rubygems/commands.
# file rubygems/commands/edit_command.rb class Gem::Commands::EditCommand < Gem::Command # ... end
See Gem::Command
for instructions on writing gem commands.
An error that indicates we weren’t able to fetch some data from a source
Used to raise parsing and loading errors
RemoteFetcher
handles the details of fetching gems and gem information from a remote source.
SpecFetcher
handles metadata updates from remote gem repositories.
The UriFormatter
handles URIs from user-input and escaping.
uf = Gem::UriFormatter.new 'example.com' p uf.normalize #=> 'http://example.com'
Format raw random number as Random
does
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:
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
A class which allows both internal and external iteration.
An Enumerator
can be created by the following methods.
Most methods have two forms: a block form where the contents are evaluated for each item in the enumeration, and a non-block form which returns a new Enumerator
wrapping the iteration.
enumerator = %w(one two three).each puts enumerator.class # => Enumerator enumerator.each_with_object("foo") do |item, obj| puts "#{obj}: #{item}" end # foo: one # foo: two # foo: three enum_with_obj = enumerator.each_with_object("foo") puts enum_with_obj.class # => Enumerator enum_with_obj.each do |item, obj| puts "#{obj}: #{item}" end # foo: one # foo: two # foo: three
This allows you to chain Enumerators together. For example, you can map a list’s elements to strings containing the index and the element as a string via:
puts %w[foo bar baz].map.with_index { |w, i| "#{i}:#{w}" } # => ["0:foo", "1:bar", "2:baz"]
An Enumerator
can also be used as an external iterator. For example, Enumerator#next
returns the next value of the iterator or raises StopIteration
if the Enumerator
is at the end.
e = [1,2,3].each # returns an enumerator object. puts e.next # => 1 puts e.next # => 2 puts e.next # => 3 puts e.next # raises StopIteration
Note that enumeration sequence by next
, next_values
, peek
and peek_values
do not affect other non-external enumeration methods, unless the underlying iteration method itself has side-effect, e.g. IO#each_line
.
Moreover, implementation typically uses fibers so performance could be slower and exception stacktraces different than expected.
You can use this to implement an internal iterator as follows:
def ext_each(e) while true begin vs = e.next_values rescue StopIteration return $!.result end y = yield(*vs) e.feed y end end o = Object.new def o.each puts yield puts yield(1) puts yield(1, 2) 3 end # use o.each as an internal iterator directly. puts o.each {|*x| puts x; [:b, *x] } # => [], [:b], [1], [:b, 1], [1, 2], [:b, 1, 2], 3 # convert o.each to an external iterator for # implementing an internal iterator. puts ext_each(o.to_enum) {|*x| puts x; [:b, *x] } # => [], [:b], [1], [:b, 1], [1, 2], [:b, 1, 2], 3