When there is an invalid block with a keyword missing an end right before another end, it is unclear where which keyword is missing the end
Take this example:
class Dog # 1 def bark # 2 puts "woof" # 3 end # 4
However due to github.com/ruby/syntax_suggest/issues/32 the problem line will be identified as:
> class Dog # 1
Because lines 2, 3, and 4 are technically valid code and are expanded first, deemed valid, and hidden. We need to un-hide the matching end line 4. Also work backwards and if there’s a mis-matched keyword, show it too
Returns self
.
Iterates backwards over array elements.
When a block given, passes, in reverse order, each element to the block; returns self
:
a = [:foo, 'bar', 2] a.reverse_each {|element| puts "#{element.class} #{element}" }
Output:
Integer 2 String bar Symbol foo
Allows the array to be modified during iteration:
a = [:foo, 'bar', 2] a.reverse_each {|element| puts element; a.clear if element.to_s.start_with?('b') }
Output:
2 bar
When no block given, returns a new Enumerator:
a = [:foo, 'bar', 2] e = a.reverse_each e # => #<Enumerator: [:foo, "bar", 2]:reverse_each> a1 = e.each {|element| puts "#{element.class} #{element}" }
Output:
Integer 2 String bar Symbol foo
Related: each
, each_index
.
Sorts the elements of self
in place, using an ordering determined by the block; returns self.
Calls the block with each successive element; sorts elements based on the values returned from the block.
For duplicates returned by the block, the ordering is indeterminate, and may be unstable.
This example sorts strings based on their sizes:
a = ['aaaa', 'bbb', 'cc', 'd'] a.sort_by! {|element| element.size } a # => ["d", "cc", "bbb", "aaaa"]
Returns a new Enumerator
if no block given:
a = ['aaaa', 'bbb', 'cc', 'd'] a.sort_by! # => #<Enumerator: ["aaaa", "bbb", "cc", "d"]:sort_by!>
Calls the block with each repeated permutation of length n
of the elements of self
; each permutation is an Array; returns self
. The order of the permutations is indeterminate.
When a block and a positive Integer
argument n
are given, calls the block with each n
-tuple repeated permutation of the elements of self
. The number of permutations is self.size**n
.
n
= 1:
a = [0, 1, 2] a.repeated_permutation(1) {|permutation| p permutation }
Output:
[0] [1] [2]
n
= 2:
a.repeated_permutation(2) {|permutation| p permutation }
Output:
[0, 0] [0, 1] [0, 2] [1, 0] [1, 1] [1, 2] [2, 0] [2, 1] [2, 2]
If n
is zero, calls the block once with an empty Array.
If n
is negative, does not call the block:
a.repeated_permutation(-1) {|permutation| fail 'Cannot happen' }
Returns a new Enumerator
if no block given:
a = [0, 1, 2] a.repeated_permutation(2) # => #<Enumerator: [0, 1, 2]:permutation(2)>
Using Enumerators, it’s convenient to show the permutations and counts for some values of n
:
e = a.repeated_permutation(0) e.size # => 1 e.to_a # => [[]] e = a.repeated_permutation(1) e.size # => 3 e.to_a # => [[0], [1], [2]] e = a.repeated_permutation(2) e.size # => 9 e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 0], [1, 1], [1, 2], [2, 0], [2, 1], [2, 2]]
Calls the block with each repeated combination of length n
of the elements of self
; each combination is an Array; returns self
. The order of the combinations is indeterminate.
When a block and a positive Integer
argument n
are given, calls the block with each n
-tuple repeated combination of the elements of self
. The number of combinations is (n+1)(n+2)/2
.
n
= 1:
a = [0, 1, 2] a.repeated_combination(1) {|combination| p combination }
Output:
[0] [1] [2]
n
= 2:
a.repeated_combination(2) {|combination| p combination }
Output:
[0, 0] [0, 1] [0, 2] [1, 1] [1, 2] [2, 2]
If n
is zero, calls the block once with an empty Array.
If n
is negative, does not call the block:
a.repeated_combination(-1) {|combination| fail 'Cannot happen' }
Returns a new Enumerator
if no block given:
a = [0, 1, 2] a.repeated_combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
Using Enumerators, it’s convenient to show the combinations and counts for some values of n
:
e = a.repeated_combination(0) e.size # => 1 e.to_a # => [[]] e = a.repeated_combination(1) e.size # => 3 e.to_a # => [[0], [1], [2]] e = a.repeated_combination(2) e.size # => 6 e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 1], [1, 2], [2, 2]]
Returns self
(which is already an Integer).
Imports methods from modules. Unlike Module#include
, Refinement#import_methods
copies methods and adds them into the refinement, so the refinement is activated in the imported methods.
Note that due to method copying, only methods defined in Ruby code can be imported.
module StrUtils def indent(level) ' ' * level + self end end module M refine String do import_methods StrUtils end end using M "foo".indent(3) #=> " foo" module M refine String do import_methods Enumerable # Can't import method which is not defined with Ruby code: Enumerable#drop end end
Returns a JSON
string representing self
:
require 'json/add/complex' puts Complex(2).to_json puts Complex(2.0, 4).to_json
Output:
{"json_class":"Complex","r":2,"i":0} {"json_class":"Complex","r":2.0,"i":4}
Returns self
as an integer; converts using method to_i
in the derived class.
Of the Core and Standard Library classes, only Rational
and Complex
use this implementation.
Examples:
Rational(1, 2).to_int # => 0 Rational(2, 1).to_int # => 2 Complex(2, 0).to_int # => 2 Complex(2, 1) # Raises RangeError (non-zero imaginary part)
Returns an array of the grapheme clusters in self
(see Unicode Grapheme Cluster Boundaries):
s = "\u0061\u0308-pqr-\u0062\u0308-xyz-\u0063\u0308" # => "ä-pqr-b̈-xyz-c̈" s.grapheme_clusters # => ["ä", "-", "p", "q", "r", "-", "b̈", "-", "x", "y", "z", "-", "c̈"]
Returns the Symbol
corresponding to str, creating the symbol if it did not previously exist. See Symbol#id2name
.
"Koala".intern #=> :Koala s = 'cat'.to_sym #=> :cat s == :cat #=> true s = '@cat'.to_sym #=> :@cat s == :@cat #=> true
This can also be used to create symbols that cannot be represented using the :xxx
notation.
'cat and dog'.to_sym #=> :"cat and dog"
Returns whether self
starts with any of the given string_or_regexp
.
Matches patterns against the beginning of self
. For each given string_or_regexp
, the pattern is:
string_or_regexp
itself, if it is a Regexp
.
Regexp.quote(string_or_regexp)
, if string_or_regexp
is a string.
Returns true
if any pattern matches the beginning, false
otherwise:
'hello'.start_with?('hell') # => true 'hello'.start_with?(/H/i) # => true 'hello'.start_with?('heaven', 'hell') # => true 'hello'.start_with?('heaven', 'paradise') # => false 'тест'.start_with?('т') # => true 'こんにちは'.start_with?('こ') # => true
Related: String#end_with?
.
Returns a copy of self
with leading substring prefix
removed:
'hello'.delete_prefix('hel') # => "lo" 'hello'.delete_prefix('llo') # => "hello" 'тест'.delete_prefix('те') # => "ст" 'こんにちは'.delete_prefix('こん') # => "にちは"
Related: String#delete_prefix!
, String#delete_suffix
.
Like String#delete_prefix
, except that self
is modified in place. Returns self
if the prefix is removed, nil
otherwise.
Changes the encoding of self
to encoding
, which may be a string encoding name or an Encoding
object; returns self:
s = 'łał' s.bytes # => [197, 130, 97, 197, 130] s.encoding # => #<Encoding:UTF-8> s.force_encoding('ascii') # => "\xC5\x82a\xC5\x82" s.encoding # => #<Encoding:US-ASCII>
Does not change the underlying bytes:
s.bytes # => [197, 130, 97, 197, 130]
Makes the change even if the given encoding
is invalid for self
(as is the change above):
s.valid_encoding? # => false s.force_encoding(Encoding::UTF_8) # => "łał" s.valid_encoding? # => true
Returns a copy of self
with Unicode normalization applied.
Argument form
must be one of the following symbols (see Unicode normalization forms):
:nfc
: Canonical decomposition, followed by canonical composition.
:nfd
: Canonical decomposition.
:nfkc
: Compatibility decomposition, followed by canonical composition.
:nfkd
: Compatibility decomposition.
The encoding of self
must be one of:
Encoding::UTF_8
Encoding::UTF_16BE
Encoding::UTF_16LE
Encoding::UTF_32BE
Encoding::UTF_32LE
Encoding::GB18030
Encoding::UCS_2BE
Encoding::UCS_4BE
Examples:
"a\u0300".unicode_normalize # => "a" "\u00E0".unicode_normalize(:nfd) # => "a "
Related: String#unicode_normalize!
, String#unicode_normalized?
.
Like String#unicode_normalize
, except that the normalization is performed on self
.
Related String#unicode_normalized?
.
Returns true
if self
is in the given form
of Unicode normalization, false
otherwise. The form
must be one of :nfc
, :nfd
, :nfkc
, or :nfkd
.
Examples:
"a\u0300".unicode_normalized? # => false "a\u0300".unicode_normalized?(:nfd) # => true "\u00E0".unicode_normalized? # => true "\u00E0".unicode_normalized?(:nfd) # => false
Raises an exception if self
is not in a Unicode encoding:
s = "\xE0".force_encoding('ISO-8859-1') s.unicode_normalized? # Raises Encoding::CompatibilityError.
Related: String#unicode_normalize
, String#unicode_normalize!
.
Returns self
truncated to an Integer
.
1.2.to_i # => 1 (-1.2).to_i # => -1
Note that the limited precision of floating-point arithmetic may lead to surprising results:
(0.3 / 0.1).to_i # => 2 (!)
Returns the next-smaller representable Float.
These examples show the internally stored values (64-bit hexadecimal) for each Float f
and for the corresponding f.pev_float
:
f = 5e-324 # 0x0000000000000001 f.prev_float # 0x0000000000000000 f = 0.01 # 0x3f847ae147ae147b f.prev_float # 0x3f847ae147ae147a
In the remaining examples here, the output is shown in the usual way (result to_s
):
0.01.prev_float # => 0.009999999999999998 1.0.prev_float # => 0.9999999999999999 100.0.prev_float # => 99.99999999999999 f = 0.01 (0..3).each_with_index {|i| printf "%2d %-20a %s\n", i, f, f.to_s; f = f.prev_float }
Output:
0 0x1.47ae147ae147bp-7 0.01 1 0x1.47ae147ae147ap-7 0.009999999999999998 2 0x1.47ae147ae1479p-7 0.009999999999999997 3 0x1.47ae147ae1478p-7 0.009999999999999995
Related: Float#next_float
.
Returns the Fiber
scheduler, that was last set for the current thread with Fiber.set_scheduler
if and only if the current fiber is non-blocking.