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.
Specifies the handling of signals. The first parameter is a signal name (a string such as “SIGALRM”, “SIGUSR1”, and so on) or a signal number. The characters “SIG” may be omitted from the signal name. The command or block specifies code to be run when the signal is raised. If the command is the string “IGNORE” or “SIG_IGN”, the signal will be ignored. If the command is “DEFAULT” or “SIG_DFL”, the Ruby’s default handler will be invoked. If the command is “EXIT”, the script will be terminated by the signal. If the command is “SYSTEM_DEFAULT”, the operating system’s default handler will be invoked. Otherwise, the given command or block will be run. The special signal name “EXIT” or signal number zero will be invoked just prior to program termination. trap returns the previous handler for the given signal.
Signal.trap(0, proc { puts "Terminating: #{$$}" }) Signal.trap("CLD") { puts "Child died" } fork && Process.wait
produces:
Terminating: 27461 Child died Terminating: 27460
Returns true if yield would execute a block in the current context. The iterator? form is mildly deprecated.
def try if block_given? yield else "no block" end end try #=> "no block" try { "hello" } #=> "hello" try do "hello" end #=> "hello"
If warnings have been disabled (for example with the -W0 flag), does nothing. Otherwise, converts each of the messages to strings, appends a newline character to the string if the string does not end in a newline, and calls Warning.warn with the string.
warn("warning 1", "warning 2")
<em>produces:</em>
warning 1
warning 2
If the uplevel keyword argument is given, the string will be prepended with information for the given caller frame in the same format used by the rb_warn C function.
# In baz.rb
def foo
warn("invalid call to foo", uplevel: 1)
end
def bar
foo
end
bar
<em>produces:</em>
baz.rb:6: warning: invalid call to foo
Returns two arrays, the first containing the elements of enum for which the block evaluates to true, the second containing the rest.
If no block is given, an enumerator is returned instead.
(1..6).partition { |v| v.even? } #=> [[2, 4, 6], [1, 3, 5]]
Passes each element of the collection to the given block. The method returns true if the block returns true exactly once. If the block is not given, one? will return true only if exactly one of the collection members is true.
If instead a pattern is supplied, the method returns whether pattern === element for exactly one collection member.
%w{ant bear cat}.one? { |word| word.length == 4 } #=> true %w{ant bear cat}.one? { |word| word.length > 4 } #=> false %w{ant bear cat}.one? { |word| word.length < 4 } #=> false %w{ant bear cat}.one?(/t/) #=> false [ nil, true, 99 ].one? #=> false [ nil, true, false ].one? #=> true [ nil, true, 99 ].one?(Integer) #=> true [].one? #=> false
Passes each element of the collection to the given block. The method returns true if the block never returns true for all elements. If the block is not given, none? will return true only if none of the collection members is true.
If instead a pattern is supplied, the method returns whether pattern === element for none of the collection members.
%w{ant bear cat}.none? { |word| word.length == 5 } #=> true %w{ant bear cat}.none? { |word| word.length >= 4 } #=> false %w{ant bear cat}.none?(/d/) #=> true [1, 3.14, 42].none?(Float) #=> false [].none? #=> true [nil].none? #=> true [nil, false].none? #=> true [nil, false, true].none? #=> false
Writes warning message msg to $stderr. This method is called by Ruby for all emitted warnings.
Enables coverage measurement.
Returns a memory pointer of a function’s hexadecimal address location val
Example:
lib = Fiddle.dlopen('/lib64/libc-2.15.so')
=> #<Fiddle::Handle:0x00000001342460>
Fiddle.dlwrap(lib['strcpy'].to_s(16))
=> 25522520
Returns the hexadecimal representation of a memory pointer address addr
Example:
lib = Fiddle.dlopen('/lib64/libc-2.15.so')
=> #<Fiddle::Handle:0x00000001342460>
lib['strcpy'].to_s(16)
=> "7f59de6dd240"
Fiddle.dlunwrap(Fiddle.dlwrap(lib['strcpy'].to_s(16)))
=> "7f59de6dd240"
Parse the JSON document source into a Ruby data structure and return it.
opts can have the following keys:
max_nesting: The maximum depth of nesting allowed in the parsed data structures. Disable depth checking with :max_nesting => false. It defaults to 100.
allow_nan: If set to true, allow NaN, Infinity and -Infinity in defiance of RFC 7159 to be parsed by the Parser. This option defaults to false.
symbolize_names: If set to true, returns symbols for the names (keys) in a JSON object. Otherwise strings are returned. Strings are the default.
create_additions: If set to false, the Parser doesn’t create additions even if a matching class and create_id was found. This option defaults to false.
object_class: Defaults to Hash
array_class: Defaults to Array
Parse the JSON document source into a Ruby data structure and return it. The bang version of the parse method defaults to the more dangerous values for the opts hash, so be sure only to parse trusted source documents.
opts can have the following keys:
max_nesting: The maximum depth of nesting allowed in the parsed data structures. Enable depth checking with :max_nesting => anInteger. The parse! methods defaults to not doing max depth checking: This can be dangerous if someone wants to fill up your stack.
allow_nan: If set to true, allow NaN, Infinity, and -Infinity in defiance of RFC 7159 to be parsed by the Parser. This option defaults to true.
create_additions: If set to false, the Parser doesn’t create additions even if a matching class and create_id was found. This option defaults to false.
See any remaining errors held in queue.
Any errors you see here are probably due to a bug in Ruby’s OpenSSL implementation.
Parse a YAML string in yaml. Returns the Psych::Nodes::Document. filename is used in the exception message if a Psych::SyntaxError is raised.
Raises a Psych::SyntaxError when a YAML syntax error is detected.
Example:
Psych.parse("---\n - a\n - b") # => #<Psych::Nodes::Document:0x00> begin Psych.parse("--- `", filename: "file.txt") rescue Psych::SyntaxError => ex ex.file # => 'file.txt' ex.message # => "(file.txt): found character that cannot start any token" end
See Psych::Nodes for more information about YAML AST.
Returns a default parser
Shows the prompt and reads the inputted line with line editing. The inputted line is added to the history if add_hist is true.
Returns nil when the inputted line is empty and user inputs EOF (Presses ^D on UNIX).
Raises IOError exception if one of below conditions are satisfied.
stdin was closed.
stdout was closed.
This method supports thread. Switches the thread context when waits inputting line.
Supports line edit when inputs line. Provides VI and Emacs editing mode. Default is Emacs editing mode.
NOTE: Terminates ruby interpreter and does not return the terminal status after user pressed ‘^C’ when wait inputting line. Give 3 examples that avoid it.
Catches the Interrupt exception by pressed ^C after returns terminal status:
require "readline"
stty_save = `stty -g`.chomp
begin
while buf = Readline.readline
p buf
end
rescue Interrupt
system("stty", stty_save)
exit
end
end
end
Catches the INT signal by pressed ^C after returns terminal status:
require "readline" stty_save = `stty -g`.chomp trap("INT") { system "stty", stty_save; exit } while buf = Readline.readline p buf end
Ignores pressing ^C:
require "readline" trap("INT", "SIG_IGN") while buf = Readline.readline p buf end
Can make as follows with Readline::HISTORY constant. It does not record to the history if the inputted line is empty or the same it as last one.
require "readline" while buf = Readline.readline("> ", true) # p Readline::HISTORY.to_a Readline::HISTORY.pop if /^\s*$/ =~ buf begin if Readline::HISTORY[Readline::HISTORY.length-2] == buf Readline::HISTORY.pop end rescue IndexError end # p Readline::HISTORY.to_a print "-> ", buf, "\n" end
Change what’s displayed on the screen to reflect the current contents.
See GNU Readline’s rl_redisplay function.
Raises NotImplementedError if the using readline library does not support.
Returns true if the syslog is open.
Returns true if the named file exists and the effective used id of the calling process is the owner of the file.
file_name can be an IO object.
Returns true if the named file exists and the effective group id of the calling process is the owner of the file. Returns false on Windows.
file_name can be an IO object.
Returns true if the named file is a character device.
file_name can be an IO object.
Initiates garbage collection, even if manually disabled.
This method is defined with keyword arguments that default to true:
def GC.start(full_mark: true, immediate_sweep: true); end
Use full_mark: false to perform a minor GC. Use immediate_sweep: false to defer sweeping (use lazy sweep).
Note: These keyword arguments are implementation and version dependent. They are not guaranteed to be future-compatible, and may be ignored if the underlying implementation does not support them.
Invokes the block with a Benchmark::Report object, which may be used to collect and report on the results of individual benchmark tests. Reserves label_width leading spaces for labels on each line. Prints caption at the top of the report, and uses format to format each line. Returns an array of Benchmark::Tms objects.
If the block returns an array of Benchmark::Tms objects, these will be used to format additional lines of output. If labels parameter are given, these are used to label these extra lines.
Note: Other methods provide a simpler interface to this one, and are suitable for nearly all benchmarking requirements. See the examples in Benchmark, and the bm and bmbm methods.
Example:
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
Generates:
user system total real for: 0.970000 0.000000 0.970000 ( 0.970493) times: 0.990000 0.000000 0.990000 ( 0.989542) upto: 0.970000 0.000000 0.970000 ( 0.972854) >total: 2.930000 0.000000 2.930000 ( 2.932889) >avg: 0.976667 0.000000 0.976667 ( 0.977630)
Invokes the block with a Benchmark::Report object, which may be used to collect and report on the results of individual benchmark tests. Reserves label_width leading spaces for labels on each line. Prints caption at the top of the report, and uses format to format each line. Returns an array of Benchmark::Tms objects.
If the block returns an array of Benchmark::Tms objects, these will be used to format additional lines of output. If labels parameter are given, these are used to label these extra lines.
Note: Other methods provide a simpler interface to this one, and are suitable for nearly all benchmarking requirements. See the examples in Benchmark, and the bm and bmbm methods.
Example:
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
Generates:
user system total real for: 0.970000 0.000000 0.970000 ( 0.970493) times: 0.990000 0.000000 0.990000 ( 0.989542) upto: 0.970000 0.000000 0.970000 ( 0.972854) >total: 2.930000 0.000000 2.930000 ( 2.932889) >avg: 0.976667 0.000000 0.976667 ( 0.977630)