Returns an arbitrary seed value. This is used by Random.new when no seed value is specified as an argument.
Random.new_seed #=> 115032730400174366788466674494640623225
Returns an array of the names of the thread-local variables (as Symbols).
thr = Thread.new do Thread.current.thread_variable_set(:cat, 'meow') Thread.current.thread_variable_set("dog", 'woof') end thr.join #=> #<Thread:0x401b3f10 dead> thr.thread_variables #=> [:dog, :cat]
Note that these are not fiber local variables. Please see Thread#[] and Thread#thread_variable_get for more details.
Returns true if the given string (or symbol) exists as a thread-local variable.
me = Thread.current me.thread_variable_set(:oliver, "a") me.thread_variable?(:oliver) #=> true me.thread_variable?(:stanley) #=> false
Note that these are not fiber local variables. Please see Thread#[] and Thread#thread_variable_get for more details.
Compiled source code (String) on *eval methods on the :script_compiled event. If loaded from a file, it will return nil.
Returns an array of the names of global variables. This includes special regexp global variables such as $~ and $+, but does not include the numbered regexp global variables ($1, $2, etc.).
global_variables.grep /std/ #=> [:$stdin, :$stdout, :$stderr]
Controls tracing of assignments to global variables. The parameter symbol identifies the variable (as either a string name or a symbol identifier). cmd (which may be a string or a Proc object) or block is executed whenever the variable is assigned. The block or Proc object receives the variable’s new value as a parameter. Also see Kernel::untrace_var.
trace_var :$_, proc {|v| puts "$_ is now '#{v}'" } $_ = "hello" $_ = ' there'
produces:
$_ is now 'hello' $_ is now ' there'
Removes tracing for the specified command on the given global variable and returns nil. If no command is specified, removes all tracing for that variable and returns an array containing the commands actually removed.
Yields self to the block and returns the result of the block.
"my string".yield_self {|s| s.upcase } #=> "MY STRING"
Good usage for then is value piping in method chains:
require 'open-uri' require 'json' construct_url(arguments). then {|url| URI(url).read }. then {|response| JSON.parse(response) }
Ruby tries to load the library named string relative to the directory containing the requiring file. If the file does not exist a LoadError is raised. Returns true if the file was loaded and false if the file was already loaded before.
Returns the names of the current local variables.
fred = 1 for i in 1..10 # ... end local_variables #=> [:fred, :i]
Returns an array containing truthy elements returned by the block.
With a block given, calls the block with successive elements; returns an array containing each truthy value returned by the block:
(0..9).filter_map {|i| i * 2 if i.even? } # => [0, 4, 8, 12, 16] {foo: 0, bar: 1, baz: 2}.filter_map {|key, value| key if value.even? } # => [:foo, :baz]
When no block given, returns an Enumerator.
Returns an array of flattened objects returned by the block.
With a block given, calls the block with successive elements; returns a flattened array of objects returned by the block:
[0, 1, 2, 3].flat_map {|element| -element } # => [0, -1, -2, -3] [0, 1, 2, 3].flat_map {|element| [element, -element] } # => [0, 0, 1, -1, 2, -2, 3, -3] [[0, 1], [2, 3]].flat_map {|e| e + [100] } # => [0, 1, 100, 2, 3, 100] {foo: 0, bar: 1, baz: 2}.flat_map {|key, value| [key, value] } # => [:foo, 0, :bar, 1, :baz, 2]
With no block given, returns an Enumerator.
Alias: collect_concat.
Calls the block with each successive overlapped n-tuple of elements; returns self:
a = [] (1..5).each_cons(3) {|element| a.push(element) } a # => [[1, 2, 3], [2, 3, 4], [3, 4, 5]] a = [] h = {foo: 0, bar: 1, baz: 2, bam: 3} h.each_cons(2) {|element| a.push(element) } a # => [[[:foo, 0], [:bar, 1]], [[:bar, 1], [:baz, 2]], [[:baz, 2], [:bam, 3]]]
With no block given, returns an Enumerator.
Calls the block with successive elements as long as the block returns a truthy value; returns an array of all elements after that point:
(1..4).drop_while{|i| i < 3 } # => [3, 4] h = {foo: 0, bar: 1, baz: 2} a = h.drop_while{|element| key, value = *element; value < 2 } a # => [[:baz, 2]]
With no block given, returns an Enumerator.
Creates an enumerator for each chunked elements. The ends of chunks are defined by pattern and the block.
If pattern === elt returns true or the block returns true for the element, the element is end of a chunk.
The === and block is called from the first element to the last element of enum.
The result enumerator yields the chunked elements as an array. So each method can be called as follows:
enum.slice_after(pattern).each { |ary| ... }
enum.slice_after { |elt| bool }.each { |ary| ... }
Other methods of the Enumerator class and Enumerable module, such as map, etc., are also usable.
For example, continuation lines (lines end with backslash) can be concatenated as follows:
lines = ["foo\n", "bar\\\n", "baz\n", "\n", "qux\n"] e = lines.slice_after(/(?<!\\)\n\z/) p e.to_a #=> [["foo\n"], ["bar\\\n", "baz\n"], ["\n"], ["qux\n"]] p e.map {|ll| ll[0...-1].map {|l| l.sub(/\\\n\z/, "") }.join + ll.last } #=>["foo\n", "barbaz\n", "\n", "qux\n"]
Makes a set from the enumerable object with given arguments. Needs to require "set" to use this method.
Returns the last Error of the current executing Thread or nil if none
Sets the last Error of the current executing Thread to error
Arguments obj and opts here are the same as arguments obj and opts in JSON.generate.
By default, generates JSON data without checking for circular references in obj (option max_nesting set to false, disabled).
Raises an exception if obj contains circular references:
a = []; b = []; a.push(b); b.push(a) # Raises SystemStackError (stack level too deep): JSON.fast_generate(a)
Arguments obj and opts here are the same as arguments obj and opts in JSON.generate.
Default options are:
{
indent: ' ', # Two spaces
space: ' ', # One space
array_nl: "\n", # Newline
object_nl: "\n" # Newline
}
Example:
obj = {foo: [:bar, :baz], bat: {bam: 0, bad: 1}} json = JSON.pretty_generate(obj) puts json
Output:
{
"foo": [
"bar",
"baz"
],
"bat": {
"bam": 0,
"bad": 1
}
}
Leaves exclusive section.
Returns true if this monitor is locked by any thread
Returns true if this monitor is locked by current thread.
Creates a new MonitorMixin::ConditionVariable associated with the Monitor object.
Adds aProc as a finalizer, to be called after obj was destroyed. The object ID of the obj will be passed as an argument to aProc. If aProc is a lambda or method, make sure it can be called with a single argument.
The return value is an array [0, aProc].
The two recommended patterns are to either create the finaliser proc in a non-instance method where it can safely capture the needed state, or to use a custom callable object that stores the needed state explicitly as instance variables.
class Foo def initialize(data_needed_for_finalization) ObjectSpace.define_finalizer(self, self.class.create_finalizer(data_needed_for_finalization)) end def self.create_finalizer(data_needed_for_finalization) proc { puts "finalizing #{data_needed_for_finalization}" } end end class Bar class Remover def initialize(data_needed_for_finalization) @data_needed_for_finalization = data_needed_for_finalization end def call(id) puts "finalizing #{@data_needed_for_finalization}" end end def initialize(data_needed_for_finalization) ObjectSpace.define_finalizer(self, Remover.new(data_needed_for_finalization)) end end
Note that if your finalizer references the object to be finalized it will never be run on GC, although it will still be run at exit. You will get a warning if you capture the object to be finalized as the receiver of the finalizer.
class CapturesSelf def initialize(name) ObjectSpace.define_finalizer(self, proc { # this finalizer will only be run on exit puts "finalizing #{name}" }) end end
Also note that finalization can be unpredictable and is never guaranteed to be run except on exit.