Results for: "max_by"

Find the best specification matching a name and requirements. Raises if the dependency doesn’t resolve to a valid specification.

Return the best specification that contains the file matching path.

Return the best specification in the record that contains the file matching path.

Remove everything in the DependencyList that matches but doesn’t satisfy items in dependencies (a hash of gem names to arrays of dependencies).

Returns every spec that matches name and optional requirements.

Find the best specification matching a full_name.

Return the best specification that contains the file matching path amongst the specs that are not activated.

Returns every spec in the record that matches name and optional requirements.

Return the best specification in the record that contains the file matching path amongst the specs that are not activated.

Returns every spec that has the given full_name

Return the best specification that contains the file matching path, among those already activated.

Return the best specification in the record that contains the file matching path, among those already activated.

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.

Raised when a gem dependencies file specifies a ruby version that does not match the current version.

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.

Raised when encountering Ruby code with an invalid syntax.

eval("1+1=2")

raises the exception:

SyntaxError: (eval):1: syntax error, unexpected '=', expecting $end

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"]

Global variables equivalence

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 Global Variables at Regexp.

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

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.

Security considerations

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.

marshal_dump and marshal_load

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

_dump and _load

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.

What’s Here

Trigonometric Functions

• ::cos: Returns the cosine of the given argument.

• ::sin: Returns the sine of the given argument.

• ::tan: Returns the tangent of the given argument.

Inverse Trigonometric Functions

• ::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.

Hyperbolic Trigonometric Functions

• ::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.

Inverse Hyperbolic Trigonometric Functions

• ::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.

Exponentiation and Logarithmic Functions

• ::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.

Fraction and Exponent Functions

• ::frexp: Returns the fraction and exponent of the given argument.

• ::ldexp: Returns the value for a given fraction and exponent.

Root Functions

• ::cbrt: Returns the cube root of the given argument.

• ::sqrt: Returns the square root of the given argument.

Error Functions

• ::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 Functions

• ::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.

Hypotenuse Function

• ::hypot: Returns sqrt(a**2 + b**2) for the given a and b.