MatchData
encapsulates the result of matching a Regexp
against string. It is returned by Regexp#match
and String#match
, and also stored in a global variable returned by Regexp.last_match
.
Usage:
url = 'https://docs.ruby-lang.org/en/2.5.0/MatchData.html' m = url.match(/(\d\.?)+/) # => #<MatchData "2.5.0" 1:"0"> m.string # => "https://docs.ruby-lang.org/en/2.5.0/MatchData.html" m.regexp # => /(\d\.?)+/ # entire matched substring: m[0] # => "2.5.0" # Working with unnamed captures m = url.match(%r{([^/]+)/([^/]+)\.html$}) m.captures # => ["2.5.0", "MatchData"] m[1] # => "2.5.0" m.values_at(1, 2) # => ["2.5.0", "MatchData"] # Working with named captures m = url.match(%r{(?<version>[^/]+)/(?<module>[^/]+)\.html$}) m.captures # => ["2.5.0", "MatchData"] m.named_captures # => {"version"=>"2.5.0", "module"=>"MatchData"} m[:version] # => "2.5.0" m.values_at(:version, :module) # => ["2.5.0", "MatchData"] # Numerical indexes are working, too m[1] # => "2.5.0" m.values_at(1, 2) # => ["2.5.0", "MatchData"]
Parts of last MatchData
(returned by Regexp.last_match
) are also aliased as global variables:
$~
is Regexp.last_match
;
$&
is Regexp.last_match
[ 0 ]
;
$1
, $2
, and so on are Regexp.last_match
[ i ]
(captures by number);
$`
is Regexp.last_match
.pre_match
;
$'
is Regexp.last_match
.post_match
;
$+
is Regexp.last_match
[ -1 ]
(the last capture).
See also “Special global variables” section in Regexp
documentation.
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)
define UnicodeNormalize module here so that we don’t have to look it up
The marshaling library converts collections of Ruby objects into a byte stream, allowing them to be stored outside the currently active script. This data may subsequently be read and the original objects reconstituted.
Marshaled data has major and minor version numbers stored along with the object information. In normal use, marshaling can only load data written with the same major version number and an equal or lower minor version number. If Ruby’s “verbose” flag is set (normally using -d, -v, -w, or –verbose) the major and minor numbers must match exactly. Marshal
versioning is independent of Ruby’s version numbers. You can extract the version by reading the first two bytes of marshaled data.
str = Marshal.dump("thing") RUBY_VERSION #=> "1.9.0" str[0].ord #=> 4 str[1].ord #=> 8
Some objects cannot be dumped: if the objects to be dumped include bindings, procedure or method objects, instances of class IO
, or singleton objects, a TypeError
will be raised.
If your class has special serialization needs (for example, if you want to serialize in some specific format), or if it contains objects that would otherwise not be serializable, you can implement your own serialization strategy.
There are two methods of doing this, your object can define either marshal_dump and marshal_load or _dump and _load. marshal_dump will take precedence over _dump if both are defined. marshal_dump may result in smaller Marshal
strings.
By design, Marshal.load
can deserialize almost any class loaded into the Ruby process. In many cases this can lead to remote code execution if the Marshal
data is loaded from an untrusted source.
As a result, Marshal.load
is not suitable as a general purpose serialization format and you should never unmarshal user supplied input or other untrusted data.
If you need to deserialize untrusted data, use JSON
or another serialization format that is only able to load simple, ‘primitive’ types such as String
, Array
, Hash
, etc. Never allow user input to specify arbitrary types to deserialize into.
When dumping an object the method marshal_dump will be called. marshal_dump must return a result containing the information necessary for marshal_load to reconstitute the object. The result can be any object.
When loading an object dumped using marshal_dump the object is first allocated then marshal_load is called with the result from marshal_dump. marshal_load must recreate the object from the information in the result.
Example:
class MyObj def initialize name, version, data @name = name @version = version @data = data end def marshal_dump [@name, @version] end def marshal_load array @name, @version = array end end
Use _dump and _load when you need to allocate the object you’re restoring yourself.
When dumping an object the instance method _dump is called with an Integer
which indicates the maximum depth of objects to dump (a value of -1 implies that you should disable depth checking). _dump must return a String
containing the information necessary to reconstitute the object.
The class method _load should take a String
and use it to return an object of the same class.
Example:
class MyObj def initialize name, version, data @name = name @version = version @data = data end def _dump level [@name, @version].join ':' end def self._load args new(*args.split(':')) end end
Since Marshal.dump
outputs a string you can have _dump return a Marshal
string which is Marshal.loaded in _load for complex objects.
Module Math provides methods for basic trigonometric, logarithmic, and transcendental functions, and for extracting roots.
You can write its constants and method calls thus:
Math::PI # => 3.141592653589793 Math::E # => 2.718281828459045 Math.sin(0.0) # => 0.0 Math.cos(0.0) # => 1.0
If you include module Math, you can write simpler forms:
include Math PI # => 3.141592653589793 E # => 2.718281828459045 sin(0.0) # => 0.0 cos(0.0) # => 1.0
For simplicity, the examples here assume:
include Math INFINITY = Float::INFINITY
The domains and ranges for the methods are denoted by open or closed intervals, using, respectively, parentheses or square brackets:
An open interval does not include the endpoints:
(-INFINITY, INFINITY)
A closed interval includes the endpoints:
[-1.0, 1.0]
A half-open interval includes one endpoint, but not the other:
[1.0, INFINITY)
Many values returned by Math methods are numerical approximations. This is because many such values are, in mathematics, of infinite precision, while in numerical computation the precision is finite.
Thus, in mathematics, cos(π/2) is exactly zero, but in our computation cos(PI/2)
is a number very close to zero:
cos(PI/2) # => 6.123031769111886e-17
For very large and very small returned values, we have added formatted numbers for clarity:
tan(PI/2) # => 1.633123935319537e+16 # 16331239353195370.0 tan(PI) # => -1.2246467991473532e-16 # -0.0000000000000001
See class Float
for the constants that affect Ruby’s floating-point arithmetic.
::cos
: Returns the cosine of the given argument.
::sin
: Returns the sine of the given argument.
::tan
: Returns the tangent of the given argument.
::acos
: Returns the arc cosine of the given argument.
::asin
: Returns the arc sine of the given argument.
::atan
: Returns the arc tangent of the given argument.
::atan2
: Returns the arg tangent of two given arguments.
::cosh
: Returns the hyperbolic cosine of the given argument.
::sinh
: Returns the hyperbolic sine of the given argument.
::tanh
: Returns the hyperbolic tangent of the given argument.
::acosh
: Returns the inverse hyperbolic cosine of the given argument.
::asinh
: Returns the inverse hyperbolic sine of the given argument.
::atanh
: Returns the inverse hyperbolic tangent of the given argument.
::exp
: Returns the value of a given value raised to a given power.
::log
: Returns the logarithm of a given value in a given base.
::log10
: Returns the base 10 logarithm of the given argument.
::log2
: Returns the base 2 logarithm of the given argument.
::frexp
: Returns the fraction and exponent of the given argument.
::ldexp
: Returns the value for a given fraction and exponent.
::cbrt
: Returns the cube root of the given argument.
::sqrt
: Returns the square root of the given argument.
::erf
: Returns the value of the Gauss error function for the given argument.
::erfc
: Returns the value of the complementary error function for the given argument.
::gamma
: Returns the value of the gamma function for the given argument.
::lgamma
: Returns the value of the logarithmic gamma function for the given argument.
::hypot
: Returns sqrt(a**2 + b**2)
for the given a
and b
.
OpenSSL::HMAC
allows computing Hash-based Message Authentication Code (HMAC
). It is a type of message authentication code (MAC) involving a hash function in combination with a key. HMAC
can be used to verify the integrity of a message as well as the authenticity.
OpenSSL::HMAC
has a similar interface to OpenSSL::Digest
.
key = "key" data = "message-to-be-authenticated" mac = OpenSSL::HMAC.hexdigest("SHA256", key, data) #=> "cddb0db23f469c8bf072b21fd837149bd6ace9ab771cceef14c9e517cc93282e"
data1 = File.binread("file1") data2 = File.binread("file2") key = "key" hmac = OpenSSL::HMAC.new(key, 'SHA256') hmac << data1 hmac << data2 mac = hmac.digest
Document-class: OpenSSL::HMAC
OpenSSL::HMAC
allows computing Hash-based Message Authentication Code (HMAC
). It is a type of message authentication code (MAC) involving a hash function in combination with a key. HMAC
can be used to verify the integrity of a message as well as the authenticity.
OpenSSL::HMAC
has a similar interface to OpenSSL::Digest
.
key = "key" data = "message-to-be-authenticated" mac = OpenSSL::HMAC.hexdigest("SHA256", key, data) #=> "cddb0db23f469c8bf072b21fd837149bd6ace9ab771cceef14c9e517cc93282e"
data1 = File.binread("file1") data2 = File.binread("file2") key = "key" hmac = OpenSSL::HMAC.new(key, 'SHA256') hmac << data1 hmac << data2 mac = hmac.digest
The error thrown when the parser encounters illegal CSV
formatting.
The DidYouMean::Formatter
is the basic, default formatter for the gem. The formatter responds to the message_for
method and it returns a human readable string.
The DidYouMean::Formatter
is the basic, default formatter for the gem. The formatter responds to the message_for
method and it returns a human readable string.
The DidYouMean::Formatter
is the basic, default formatter for the gem. The formatter responds to the message_for
method and it returns a human readable string.
Default formatter for log messages.
Parent class for informational (1xx) HTTP
response classes.
An informational response indicates that the request was received and understood.
References:
Response class for Non-Authoritative Information
responses (status code 203).
The Non-Authoritative Information
response indicates that the server is a transforming proxy (such as a Web accelerator) that received a 200 OK response from its origin, and is returning a modified version of the origin’s response.
References:
Response class for Moved Permanently
responses (status code 301).
The Moved Permanently
response indicates that links or records returning this response should be updated to use the given URL.
References:
Response class for Permanent Redirect
responses (status code 308).
This and all future requests should be directed to the given URI
.
References:
Response class for Too Many Requests
responses (status code 429).
The user has sent too many requests in a given amount of time.
References: