Returns a new Array that is the union of self and all given Arrays other_arrays; duplicates are removed; order is preserved; items are compared using eql?:
[0, 1, 2, 3].union([4, 5], [6, 7]) # => [0, 1, 2, 3, 4, 5, 6, 7] [0, 1, 1].union([2, 1], [3, 1]) # => [0, 1, 2, 3] [0, 1, 2, 3].union([3, 2], [1, 0]) # => [0, 1, 2, 3]
Returns a copy of self if no arguments given.
Related: Array#|.
When invoked with a block, yield all permutations of elements of self; returns self. The order of permutations is indeterminate.
When a block and an in-range positive Integer argument n (0 < n <= self.size) are given, calls the block with all n-tuple permutations of self.
Example:
a = [0, 1, 2] a.permutation(2) {|permutation| p permutation }
Output:
[0, 1] [0, 2] [1, 0] [1, 2] [2, 0] [2, 1]
Another example:
a = [0, 1, 2] a.permutation(3) {|permutation| p permutation }
Output:
[0, 1, 2] [0, 2, 1] [1, 0, 2] [1, 2, 0] [2, 0, 1] [2, 1, 0]
When n is zero, calls the block once with a new empty Array:
a = [0, 1, 2] a.permutation(0) {|permutation| p permutation }
Output:
[]
When n is out of range (negative or larger than self.size), does not call the block:
a = [0, 1, 2] a.permutation(-1) {|permutation| fail 'Cannot happen' } a.permutation(4) {|permutation| fail 'Cannot happen' }
When a block given but no argument, behaves the same as a.permutation(a.size):
a = [0, 1, 2] a.permutation {|permutation| p permutation }
Output:
[0, 1, 2] [0, 2, 1] [1, 0, 2] [1, 2, 0] [2, 0, 1] [2, 1, 0]
Returns a new Enumerator if no block given:
a = [0, 1, 2] a.permutation # => #<Enumerator: [0, 1, 2]:permutation> a.permutation(2) # => #<Enumerator: [0, 1, 2]:permutation(2)>
Calls the block, if given, with combinations of elements of self; returns self. The order of combinations is indeterminate.
When a block and an in-range positive Integer argument n (0 < n <= self.size) are given, calls the block with all n-tuple combinations of self.
Example:
a = [0, 1, 2] a.combination(2) {|combination| p combination }
Output:
[0, 1] [0, 2] [1, 2]
Another example:
a = [0, 1, 2] a.combination(3) {|combination| p combination }
Output:
[0, 1, 2]
When n is zero, calls the block once with a new empty Array:
a = [0, 1, 2] a1 = a.combination(0) {|combination| p combination }
Output:
[]
When n is out of range (negative or larger than self.size), does not call the block:
a = [0, 1, 2] a.combination(-1) {|combination| fail 'Cannot happen' } a.combination(4) {|combination| fail 'Cannot happen' }
Returns a new Enumerator if no block given:
a = [0, 1, 2] a.combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
Returns the value as a rational. The optional argument eps is always ignored.
Returns a Rational object whose value is exactly or approximately equivalent to that of self.real.
With no argument epsilon given, returns a Rational object whose value is exactly equal to that of self.real.rationalize:
Complex.rect(1, 0).rationalize # => (1/1) Complex.rect(1, Rational(0, 1)).rationalize # => (1/1) Complex.rect(3.14159, 0).rationalize # => (314159/100000)
With argument epsilon given, returns a Rational object whose value is exactly or approximately equal to that of self.real to the given precision:
Complex.rect(3.14159, 0).rationalize(0.1) # => (16/5) Complex.rect(3.14159, 0).rationalize(0.01) # => (22/7) Complex.rect(3.14159, 0).rationalize(0.001) # => (201/64) Complex.rect(3.14159, 0).rationalize(0.0001) # => (333/106) Complex.rect(3.14159, 0).rationalize(0.00001) # => (355/113) Complex.rect(3.14159, 0).rationalize(0.000001) # => (7433/2366) Complex.rect(3.14159, 0).rationalize(0.0000001) # => (9208/2931) Complex.rect(3.14159, 0).rationalize(0.00000001) # => (47460/15107) Complex.rect(3.14159, 0).rationalize(0.000000001) # => (76149/24239) Complex.rect(3.14159, 0).rationalize(0.0000000001) # => (314159/100000) Complex.rect(3.14159, 0).rationalize(0.0) # => (3537115888337719/1125899906842624)
Related: Complex#to_r.
Returns zero as a Rational:
nil.rationalize # => (0/1)
Argument eps is ignored.
Returns a simpler approximation of the value (flt-|eps| <= result <= flt+|eps|). If the optional argument eps is not given, it will be chosen automatically.
0.3.rationalize #=> (3/10) 1.333.rationalize #=> (1333/1000) 1.333.rationalize(0.01) #=> (4/3)
See also Float#to_r.
Returns an exception object of the same class as self; useful for creating a similar exception, but with a different message.
With message nil, returns self:
x0 = StandardError.new('Boom') # => #<StandardError: Boom> x1 = x0.exception # => #<StandardError: Boom> x0.__id__ == x1.__id__ # => true
With string-convertible object message (even the same as the original message), returns a new exception object whose class is the same as self, and whose message is the given message:
x1 = x0.exception('Boom') # => #<StandardError: Boom> x0..equal?(x1) # => false
Returns an exception object of the same class as self; useful for creating a similar exception, but with a different message.
With message nil, returns self:
x0 = StandardError.new('Boom') # => #<StandardError: Boom> x1 = x0.exception # => #<StandardError: Boom> x0.__id__ == x1.__id__ # => true
With string-convertible object message (even the same as the original message), returns a new exception object whose class is the same as self, and whose message is the given message:
x1 = x0.exception('Boom') # => #<StandardError: Boom> x0..equal?(x1) # => false
Returns a simpler approximation of the value if the optional argument eps is given (rat-|eps| <= result <= rat+|eps|), self otherwise.
r = Rational(5033165, 16777216) r.rationalize #=> (5033165/16777216) r.rationalize(Rational('0.01')) #=> (3/10) r.rationalize(Rational('0.1')) #=> (1/3)
Returns a new regexp that is the union of the given patterns:
r = Regexp.union(%w[cat dog]) # => /cat|dog/ r.match('cat') # => #<MatchData "cat"> r.match('dog') # => #<MatchData "dog"> r.match('cog') # => nil
For each pattern that is a string, Regexp.new(pattern) is used:
Regexp.union('penzance') # => /penzance/ Regexp.union('a+b*c') # => /a\+b\*c/ Regexp.union('skiing', 'sledding') # => /skiing|sledding/ Regexp.union(['skiing', 'sledding']) # => /skiing|sledding/
For each pattern that is a regexp, it is used as is, including its flags:
Regexp.union(/foo/i, /bar/m, /baz/x) # => /(?i-mx:foo)|(?m-ix:bar)|(?x-mi:baz)/ Regexp.union([/foo/i, /bar/m, /baz/x]) # => /(?i-mx:foo)|(?m-ix:bar)|(?x-mi:baz)/
With no arguments, returns /(?!)/:
Regexp.union # => /(?!)/
If any regexp pattern contains captures, the behavior is unspecified.
Returns an integer whose bits show the options set in self.
The option bits are:
Regexp::IGNORECASE # => 1 Regexp::EXTENDED # => 2 Regexp::MULTILINE # => 4
Examples:
/foo/.options # => 0 /foo/i.options # => 1 /foo/x.options # => 2 /foo/m.options # => 4 /foo/mix.options # => 7
Note that additional bits may be set in the returned integer; these are maintained internally in self, are ignored if passed to Regexp.new, and may be ignored by the caller:
Returns the set of bits corresponding to the options used when creating this regexp (see Regexp::new for details). Note that additional bits may be set in the returned options: these are used internally by the regular expression code. These extra bits are ignored if the options are passed to Regexp::new:
r = /\xa1\xa2/e # => /\xa1\xa2/ r.source # => "\\xa1\\xa2" r.options # => 16 Regexp.new(r.source, r.options) # => /\xa1\xa2/
Sets optional filename and line number that will be used in ERB code evaluation and error reporting. See also filename= and lineno=
erb = ERB.new('<%= some_x %>') erb.render # undefined local variable or method `some_x' # from (erb):1 erb.location = ['file.erb', 3] # All subsequent error reporting would use new location erb.render # undefined local variable or method `some_x' # from file.erb:4
Returns x/y or arg as a Rational.
Rational(2, 3) #=> (2/3) Rational(5) #=> (5/1) Rational(0.5) #=> (1/2) Rational(0.3) #=> (5404319552844595/18014398509481984) Rational("2/3") #=> (2/3) Rational("0.3") #=> (3/10) Rational("10 cents") #=> ArgumentError Rational(nil) #=> TypeError Rational(1, nil) #=> TypeError Rational("10 cents", exception: false) #=> nil
Syntax of the string form:
string form = extra spaces , rational , extra spaces ;
rational = [ sign ] , unsigned rational ;
unsigned rational = numerator | numerator , "/" , denominator ;
numerator = integer part | fractional part | integer part , fractional part ;
denominator = digits ;
integer part = digits ;
fractional part = "." , digits , [ ( "e" | "E" ) , [ sign ] , digits ] ;
sign = "-" | "+" ;
digits = digit , { digit | "_" , digit } ;
digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
extra spaces = ? \s* ? ;
See also String#to_r.
Returns an array of the string keyword names:
FileUtils.options.take(3) # => ["noop", "verbose", "force"]
Returns the Fiber scheduler, that was last set for the current thread with Fiber.set_scheduler. Returns nil if no scheduler is set (which is the default), and non-blocking fibers’ behavior is the same as blocking. (see “Non-blocking fibers” section in class docs for details about the scheduler concept).
The method is expected to immediately run the provided block of code in a separate non-blocking fiber.
puts "Go to sleep!" Fiber.set_scheduler(MyScheduler.new) Fiber.schedule do puts "Going to sleep" sleep(1) puts "I slept well" end puts "Wakey-wakey, sleepyhead"
Assuming MyScheduler is properly implemented, this program will produce:
Go to sleep! Going to sleep Wakey-wakey, sleepyhead ...1 sec pause here... I slept well
…e.g. on the first blocking operation inside the Fiber (sleep(1)), the control is yielded to the outside code (main fiber), and at the end of that execution, the scheduler takes care of properly resuming all the blocked fibers.
Note that the behavior described above is how the method is expected to behave, actual behavior is up to the current scheduler’s implementation of Fiber::Scheduler#fiber method. Ruby doesn’t enforce this method to behave in any particular way.
If the scheduler is not set, the method raises RuntimeError (No scheduler is available!).
Raises PStore::Error if the calling code is not in a PStore#transaction or if the code is in a read-only PStore#transaction.
Returns the status of the global “abort on exception” condition.
The default is false.
When set to true, if any thread is aborted by an exception, the raised exception will be re-raised in the main thread.
Can also be specified by the global $DEBUG flag or command line option -d.
See also ::abort_on_exception=.
There is also an instance level method to set this for a specific thread, see abort_on_exception.
When set to true, if any thread is aborted by an exception, the raised exception will be re-raised in the main thread. Returns the new state.
Thread.abort_on_exception = true t1 = Thread.new do puts "In new thread" raise "Exception from thread" end sleep(1) puts "not reached"
This will produce:
In new thread prog.rb:4: Exception from thread (RuntimeError) from prog.rb:2:in `initialize' from prog.rb:2:in `new' from prog.rb:2
See also ::abort_on_exception.
There is also an instance level method to set this for a specific thread, see abort_on_exception=.
Returns the status of the global “report on exception” condition.
The default is true since Ruby 2.5.
All threads created when this flag is true will report a message on $stderr if an exception kills the thread.
Thread.new { 1.times { raise } }
will produce this output on $stderr:
#<Thread:...> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
2: from -e:1:in `block in <main>'
1: from -e:1:in `times'
This is done to catch errors in threads early. In some cases, you might not want this output. There are multiple ways to avoid the extra output:
If the exception is not intended, the best is to fix the cause of the exception so it does not happen anymore.
If the exception is intended, it might be better to rescue it closer to where it is raised rather then let it kill the Thread.
If it is guaranteed the Thread will be joined with Thread#join or Thread#value, then it is safe to disable this report with Thread.current.report_on_exception = false when starting the Thread. However, this might handle the exception much later, or not at all if the Thread is never joined due to the parent thread being blocked, etc.
See also ::report_on_exception=.
There is also an instance level method to set this for a specific thread, see report_on_exception=.
Returns the new state. When set to true, all threads created afterwards will inherit the condition and report a message on $stderr if an exception kills a thread:
Thread.report_on_exception = true t1 = Thread.new do puts "In new thread" raise "Exception from thread" end sleep(1) puts "In the main thread"
This will produce:
In new thread #<Thread:...prog.rb:2> terminated with exception (report_on_exception is true): Traceback (most recent call last): prog.rb:4:in `block in <main>': Exception from thread (RuntimeError) In the main thread
See also ::report_on_exception.
There is also an instance level method to set this for a specific thread, see report_on_exception=.
Returns the status of the thread-local “abort on exception” condition for this thr.
The default is false.
See also abort_on_exception=.
There is also a class level method to set this for all threads, see ::abort_on_exception.
When set to true, if this thr is aborted by an exception, the raised exception will be re-raised in the main thread.
See also abort_on_exception.
There is also a class level method to set this for all threads, see ::abort_on_exception=.