Deprecated. Use block_given? instead.
Repeatedly executes the block.
If no block is given, an enumerator is returned instead.
loop do print "Input: " line = gets break if !line or line =~ /^qQ/ # ... end
StopIteration raised in the block breaks the loop. In this case, loop returns the “result” value stored in the exception.
enum = Enumerator.new { |y| y << "one" y << "two" :ok } result = loop { puts enum.next } #=> :ok
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
If category keyword argument is given, passes the category to Warning.warn. The category given must be be one of the following categories:
Used for warning for deprecated functionality that may be removed in the future.
Used for experimental features that may change in future releases.
Returns an array containing elements selected by the block.
With a block given, calls the block with successive elements; returns an array of those elements for which the block returns a truthy value:
(0..9).select {|element| element % 3 == 0 } # => [0, 3, 6, 9] a = {foo: 0, bar: 1, baz: 2}.select {|key, value| key.start_with?('b') } a # => {:bar=>1, :baz=>2}
With no block given, returns an Enumerator.
Related: reject.
Returns an array containing elements selected by the block.
With a block given, calls the block with successive elements; returns an array of those elements for which the block returns a truthy value:
(0..9).select {|element| element % 3 == 0 } # => [0, 3, 6, 9] a = {foo: 0, bar: 1, baz: 2}.select {|key, value| key.start_with?('b') } a # => {:bar=>1, :baz=>2}
With no block given, returns an Enumerator.
Related: reject.
Returns the first element or elements.
With no argument, returns the first element, or nil if there is none:
(1..4).first # => 1 %w[a b c].first # => "a" {foo: 1, bar: 1, baz: 2}.first # => [:foo, 1] [].first # => nil
With integer argument n, returns an array containing the first n elements that exist:
(1..4).first(2) # => [1, 2] %w[a b c d].first(3) # => ["a", "b", "c"] %w[a b c d].first(50) # => ["a", "b", "c", "d"] {foo: 1, bar: 1, baz: 2}.first(2) # => [[:foo, 1], [:bar, 1]] [].first(2) # => []
Returns whether exactly one element meets a given criterion.
With no argument and no block, returns whether exactly one element is truthy:
(1..1).one? # => true [1, nil, false].one? # => true (1..4).one? # => false {foo: 0}.one? # => true {foo: 0, bar: 1}.one? # => false [].one? # => false
With argument pattern and no block, returns whether for exactly one element element, pattern === element:
[nil, false, 0].one?(Integer) # => true [nil, false, 0].one?(Numeric) # => true [nil, false, 0].one?(Float) # => false %w[bar baz bat bam].one?(/m/) # => true %w[bar baz bat bam].one?(/foo/) # => false %w[bar baz bat bam].one?('ba') # => false {foo: 0, bar: 1, baz: 2}.one?(Array) # => false {foo: 0}.one?(Array) # => true [].one?(Integer) # => false
With a block given, returns whether the block returns a truthy value for exactly one element:
(1..4).one? {|element| element < 2 } # => true (1..4).one? {|element| element < 1 } # => false {foo: 0, bar: 1, baz: 2}.one? {|key, value| value < 1 } # => true {foo: 0, bar: 1, baz: 2}.one? {|key, value| value < 2 } # => false
Returns whether no element meets a given criterion.
With no argument and no block, returns whether no element is truthy:
(1..4).none? # => false [nil, false].none? # => true {foo: 0}.none? # => false {foo: 0, bar: 1}.none? # => false [].none? # => true
With argument pattern and no block, returns whether for no element element, pattern === element:
[nil, false, 1.1].none?(Integer) # => true %w[bar baz bat bam].none?(/m/) # => false %w[bar baz bat bam].none?(/foo/) # => true %w[bar baz bat bam].none?('ba') # => true {foo: 0, bar: 1, baz: 2}.none?(Hash) # => true {foo: 0}.none?(Array) # => false [].none?(Integer) # => true
With a block given, returns whether the block returns a truthy value for no element:
(1..4).none? {|element| element < 1 } # => true (1..4).none? {|element| element < 2 } # => false {foo: 0, bar: 1, baz: 2}.none? {|key, value| value < 0 } # => true {foo: 0, bar: 1, baz: 2}.none? {|key, value| value < 1 } # => false
Returns whether for any element object == element:
(1..4).include?(2) # => true (1..4).include?(5) # => false (1..4).include?('2') # => false %w[a b c d].include?('b') # => true %w[a b c d].include?('2') # => false {foo: 0, bar: 1, baz: 2}.include?(:foo) # => true {foo: 0, bar: 1, baz: 2}.include?('foo') # => false {foo: 0, bar: 1, baz: 2}.include?(0) # => false
Enumerable#member? is an alias for Enumerable#include?.
For positive integer n, returns an array containing all but the first n elements:
r = (1..4) r.drop(3) # => [4] r.drop(2) # => [3, 4] r.drop(1) # => [2, 3, 4] r.drop(0) # => [1, 2, 3, 4] r.drop(50) # => [] h = {foo: 0, bar: 1, baz: 2, bat: 3} h.drop(2) # => [[:baz, 2], [:bat, 3]]
Returns an array of all non-nil elements:
a = [nil, 0, nil, 'a', false, nil, false, nil, 'a', nil, 0, nil] a.compact # => [0, "a", false, false, "a", 0]
Writes warning message msg to $stderr. This method is called by Ruby for all emitted warnings. A category may be included with the warning.
See the documentation of the Warning module for how to customize this.
Determines the equality of two numbers by comparing to zero, or using the epsilon value
Set up the coverage measurement.
Note that this method does not start the measurement itself. Use Coverage.resume to start the measurement.
You may want to use Coverage.start to setup and then start the measurement.
Enables the coverage measurement. See the documentation of Coverage class in detail. This is equivalent to Coverage.setup and Coverage.resume.
Resets the process of reading the /etc/passwd file, so that the next call to ::getpwent will return the first entry again.
Provides a convenient Ruby iterator which executes a block for each entry in the /etc/passwd file.
The code block is passed an Passwd struct.
See ::getpwent above for details.
Example:
require 'etc' Etc.passwd {|u| puts u.name + " = " + u.gecos }
Resets the process of reading the /etc/group file, so that the next call to ::getgrent will return the first entry again.
Returns system configuration directory.
This is typically “/etc”, but is modified by the prefix used when Ruby was compiled. For example, if Ruby is built and installed in /usr/local, returns “/usr/local/etc” on other platforms than Windows. On Windows, this always returns the directory provided by the system.
Returns system configuration variable using sysconf().
name should be a constant under Etc which begins with SC_.
The return value is an integer or nil. nil means indefinite limit. (sysconf() returns -1 but errno is not set.)
Etc.sysconf(Etc::SC_ARG_MAX) #=> 2097152 Etc.sysconf(Etc::SC_LOGIN_NAME_MAX) #=> 256
Returns system configuration variable using confstr().
name should be a constant under Etc which begins with CS_.
The return value is a string or nil. nil means no configuration-defined value. (confstr() returns 0 but errno is not set.)
Etc.confstr(Etc::CS_PATH) #=> "/bin:/usr/bin" # GNU/Linux Etc.confstr(Etc::CS_GNU_LIBC_VERSION) #=> "glibc 2.18" Etc.confstr(Etc::CS_GNU_LIBPTHREAD_VERSION) #=> "NPTL 2.18"
Creates a new handler that opens library, and returns an instance of Fiddle::Handle.
If nil is given for the library, Fiddle::Handle::DEFAULT is used, which is the equivalent to RTLD_DEFAULT. See man 3 dlopen for more.
lib = Fiddle.dlopen(nil)
The default is dependent on OS, and provide a handle for all libraries already loaded. For example, in most cases you can use this to access libc functions, or ruby functions like rb_str_new.
See Fiddle::Handle.new for more.
Creates a new handler that opens library, and returns an instance of Fiddle::Handle.
If nil is given for the library, Fiddle::Handle::DEFAULT is used, which is the equivalent to RTLD_DEFAULT. See man 3 dlopen for more.
lib = Fiddle.dlopen(nil)
The default is dependent on OS, and provide a handle for all libraries already loaded. For example, in most cases you can use this to access libc functions, or ruby functions like rb_str_new.
See Fiddle::Handle.new for more.
Returns a String containing the generated JSON data.
See also JSON.fast_generate, JSON.pretty_generate.
Argument obj is the Ruby object to be converted to JSON.
Argument opts, if given, contains a Hash of options for the generation. See Generating Options.
When obj is an Array, returns a String containing a JSON array:
obj = ["foo", 1.0, true, false, nil] json = JSON.generate(obj) json # => '["foo",1.0,true,false,null]'
When obj is a Hash, returns a String containing a JSON object:
obj = {foo: 0, bar: 's', baz: :bat} json = JSON.generate(obj) json # => '{"foo":0,"bar":"s","baz":"bat"}'
For examples of generating from other Ruby objects, see Generating JSON from Other Objects.
Raises an exception if any formatting option is not a String.
Raises an exception if obj contains circular references:
a = []; b = []; a.push(b); b.push(a) # Raises JSON::NestingError (nesting of 100 is too deep): JSON.generate(a)
Encodes string using String.encode.