Returns a new Array
containing those elements from self
that are not duplicates, the first occurrence always being retained.
With no block given, identifies and omits duplicates using method eql?
to compare:
a = [0, 0, 1, 1, 2, 2] a.uniq # => [0, 1, 2]
With a block given, calls the block for each element; identifies (using method eql?
) and omits duplicate values, that is, those elements for which the block returns the same value:
a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb'] a.uniq {|element| element.size } # => ["a", "aa", "aaa"]
With no block, returns a new array containing only unique elements; the array has no two elements e0
and e1
such that e0.eql?(e1)
:
%w[a b c c b a a b c].uniq # => ["a", "b", "c"] [0, 1, 2, 2, 1, 0, 0, 1, 2].uniq # => [0, 1, 2]
With a block, returns a new array containing elements only for which the block returns a unique value:
a = [0, 1, 2, 3, 4, 5, 5, 4, 3, 2, 1] a.uniq {|i| i.even? ? i : 0 } # => [0, 2, 4] a = %w[a b c d e e d c b a a b c d e] a.uniq {|c| c < 'c' } # => ["a", "c"]
Like Enumerable#uniq
, but chains operation to be lazy-evaluated.
Like Enumerable#uniq
, but chains operation to be lazy-evaluated.
UNIXServer
represents a UNIX domain stream server socket.
UNIXSocket
represents a UNIX domain stream client socket.
Ruby supports two forms of objectified methods. Class
Method
is used to represent methods that are associated with a particular object: these method objects are bound to that object. Bound method objects for an object can be created using Object#method
.
Ruby also supports unbound methods; methods objects that are not associated with a particular object. These can be created either by calling Module#instance_method
or by calling unbind on a bound method object. The result of both of these is an UnboundMethod
object.
Unbound methods can only be called after they are bound to an object. That object must be a kind_of? the method’s original class.
class Square def area @side * @side end def initialize(side) @side = side end end area_un = Square.instance_method(:area) s = Square.new(12) area = area_un.bind(s) area.call #=> 144
Unbound methods are a reference to the method at the time it was objectified: subsequent changes to the underlying class will not affect the unbound method.
class Test def test :original end end um = Test.instance_method(:test) class Test def test :modified end end t = Test.new t.test #=> :modified um.bind(t).call #=> :original
define UnicodeNormalize module here so that we don’t have to look it up
A base class for objects representing a C union
A pointer to a C union
This exception is raised if the required unicode support is missing on the system. Usually this means that the iconv library is not installed.
Raised when removing a gem with the uninstall command fails
An Uninstaller
.
The uninstaller fires pre and post uninstall hooks. Hooks can be added either through a rubygems_plugin.rb file in an installed gem or via a rubygems/defaults/#{RUBY_ENGINE}.rb or rubygems/defaults/operating_system.rb file. See Gem.pre_uninstall
and Gem.post_uninstall
for details.
Helper methods for both Gem::Installer
and Gem::Uninstaller
The class of the singleton object nil
.
Several of its methods act as operators:
Others act as converters, carrying the concept of nullity to other classes:
Another method provides inspection:
Finally, there is this query method:
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
Use the Monitor
class when you want to have a lock object for blocks with mutual exclusion.
require 'monitor' lock = Monitor.new lock.synchronize do # exclusive access end
Raised when throw
is called with a tag which does not have corresponding catch
block.
throw "foo", "bar"
raises the exception:
UncaughtThrowError: uncaught throw "foo"
The Warning
module contains a single method named warn
, and the module extends itself, making Warning.warn
available. Warning.warn
is called for all warnings issued by Ruby. By default, warnings are printed to $stderr.
Changing the behavior of Warning.warn
is useful to customize how warnings are handled by Ruby, for instance by filtering some warnings, and/or outputting warnings somewhere other than $stderr
.
If you want to change the behavior of Warning.warn
you should use Warning.extend(MyNewModuleWithWarnMethod)
and you can use super
to get the default behavior of printing the warning to $stderr
.
Example:
module MyWarningFilter def warn(message, category: nil, **kwargs) if /some warning I want to ignore/.match?(message) # ignore else super end end end Warning.extend MyWarningFilter
You should never redefine Warning#warn
(the instance method), as that will then no longer provide a way to use the default behavior.
The warning gem provides convenient ways to customize Warning.warn
.
In concurrent programming, a monitor is an object or module intended to be used safely by more than one thread. The defining characteristic of a monitor is that its methods are executed with mutual exclusion. That is, at each point in time, at most one thread may be executing any of its methods. This mutual exclusion greatly simplifies reasoning about the implementation of monitors compared to reasoning about parallel code that updates a data structure.
You can read more about the general principles on the Wikipedia page for Monitors.
require 'monitor.rb' buf = [] buf.extend(MonitorMixin) empty_cond = buf.new_cond # consumer Thread.start do loop do buf.synchronize do empty_cond.wait_while { buf.empty? } print buf.shift end end end # producer while line = ARGF.gets buf.synchronize do buf.push(line) empty_cond.signal end end
The consumer thread waits for the producer thread to push a line to buf while buf.empty?
. The producer thread (main thread) reads a line from ARGF
and pushes it into buf then calls empty_cond.signal
to notify the consumer thread of new data.
Class
include require 'monitor' class SynchronizedArray < Array include MonitorMixin def initialize(*args) super(*args) end alias :old_shift :shift alias :old_unshift :unshift def shift(n=1) self.synchronize do self.old_shift(n) end end def unshift(item) self.synchronize do self.old_unshift(item) end end # other methods ... end
SynchronizedArray
implements an Array
with synchronized access to items. This Class
is implemented as subclass of Array
which includes the MonitorMixin
module.
A representation of a C function
@libc = Fiddle.dlopen "/lib/libc.so.6" #=> #<Fiddle::Handle:0x00000001d7a8d8> f = Fiddle::Function.new( @libc['strcpy'], [Fiddle::TYPE_VOIDP, Fiddle::TYPE_VOIDP], Fiddle::TYPE_VOIDP) #=> #<Fiddle::Function:0x00000001d8ee00> buff = "000" #=> "000" str = f.call(buff, "123") #=> #<Fiddle::Pointer:0x00000001d0c380 ptr=0x000000018a21b8 size=0 free=0x00000000000000> str.to_s => "123"
@libc = Fiddle.dlopen "/lib/libc.so.6" #=> #<Fiddle::Handle:0x00000001d7a8d8> f = Fiddle::Function.new(@libc['strcpy'], [TYPE_VOIDP, TYPE_VOIDP], TYPE_VOIDP) #=> #<Fiddle::Function:0x00000001d8ee00> f.abi == Fiddle::Function::DEFAULT #=> true
Raised when OLE processing failed.
EX:
obj = WIN32OLE.new("NonExistProgID")
raises the exception:
WIN32OLE::RuntimeError: unknown OLE server: `NonExistProgID' HRESULT error code:0x800401f3 Invalid class string