Returns the hash of available encoding alias and original encoding name.
Encoding.aliases
#=> {"BINARY"=>"ASCII-8BIT", "ASCII"=>"US-ASCII", "ANSI_X3.4-1968"=>"US-ASCII",
"SJIS"=>"Windows-31J", "eucJP"=>"EUC-JP", "CP932"=>"Windows-31J"}
Returns the receiver.
string = "my string" string.itself.object_id == string.object_id #=> true
Invokes the method identified by symbol, passing it any arguments specified. When the method is identified by a string, the string is converted to a symbol.
BasicObject implements __send__, Kernel implements send. __send__ is safer than send when obj has the same method name like Socket. See also public_send.
class Klass def hello(*args) "Hello " + args.join(' ') end end k = Klass.new k.send :hello, "gentle", "readers" #=> "Hello gentle readers"
Returns the previous exception ($!) at the time this exception was raised. This is useful for wrapping exceptions and retaining the original exception information.
Return the receiver associated with this KeyError exception.
Return the receiver associated with this NameError exception.
Return the arguments passed in as the third parameter to the constructor.
Return the receiver associated with this FrozenError exception.
Return this SystemCallError’s error number.
Returns the list of Modules nested at the point of call.
module M1 module M2 $a = Module.nesting end end $a #=> [M1::M2, M1] $a[0].name #=> "M1::M2"
In the first form, returns an array of the names of all constants accessible from the point of call. This list includes the names of all modules and classes defined in the global scope.
Module.constants.first(4) # => [:ARGF, :ARGV, :ArgumentError, :Array] Module.constants.include?(:SEEK_SET) # => false class IO Module.constants.include?(:SEEK_SET) # => true end
The second form calls the instance method constants.
Returns a list of modules included/prepended in mod (including mod itself).
module Mod include Math include Comparable prepend Enumerable end Mod.ancestors #=> [Enumerable, Mod, Comparable, Math] Math.ancestors #=> [Math] Enumerable.ancestors #=> [Enumerable]
Returns an array of the names of the constants accessible in mod. This includes the names of constants in any included modules (example at start of section), unless the inherit parameter is set to false.
The implementation makes no guarantees about the order in which the constants are yielded.
IO.constants.include?(:SYNC) #=> true IO.constants(false).include?(:SYNC) #=> false
Also see Module#const_defined?.
Returns the remainder from dividing by the value.
x.remainder(y) means x-y*(x/y).truncate
Returns the value raised to the power of n.
Note that n must be an Integer.
Also available as the operator **.
Returns True if the value is zero.
The coerce method provides support for Ruby type coercion. It is not enabled by default.
This means that binary operations like + * / or - can often be performed on a BigDecimal and an object of another type, if the other object can be coerced into a BigDecimal value.
e.g.
a = BigDecimal("1.0") b = a / 2.0 #=> 0.5
Note that coercing a String to a BigDecimal is not supported by default; it requires a special compile-time option when building Ruby.
Returns the exponent of the BigDecimal number, as an Integer.
If the number can be represented as 0.xxxxxx*10**n where xxxxxx is a string of digits with no leading zeros, then n is the exponent.
Returns the numerator.
Rational(7).numerator #=> 7 Rational(7, 1).numerator #=> 7 Rational(9, -4).numerator #=> -9 Rational(-2, -10).numerator #=> 1
Returns true if rat is greater than 0.
Returns true if rat is less than 0.
Synonym for $stdin.
This method is an alias for http_header, when HTML5 tag maker is inactive.
NOTE: use http_header to create HTTP header blocks, this alias is only provided for backwards compatibility.
Using header with the HTML5 tag maker will create a <header> element.
Returns a new Date object constructed from the arguments.
Argument cwyear gives the year, and should be an integer.
Argument cweek gives the index of the week within the year, and should be in range (1..53) or (-53..-1); in some years, 53 or -53 will be out-of-range; if negative, counts backward from the end of the year:
Date.commercial(2022, 1, 1).to_s # => "2022-01-03" Date.commercial(2022, 52, 1).to_s # => "2022-12-26"
Argument cwday gives the indes of the weekday within the week, and should be in range (1..7) or (-7..-1); 1 or -7 is Monday; if negative, counts backward from the end of the week:
Date.commercial(2022, 1, 1).to_s # => "2022-01-03" Date.commercial(2022, 1, -7).to_s # => "2022-01-03"
When cweek is 1:
If January 1 is a Friday, Saturday, or Sunday, the first week begins in the week after:
Date::ABBR_DAYNAMES[Date.new(2023, 1, 1).wday] # => "Sun" Date.commercial(2023, 1, 1).to_s # => "2023-01-02" Date.commercial(2023, 1, 7).to_s # => "2023-01-08"
Otherwise, the first week is the week of January 1, which may mean some of the days fall on the year before:
Date::ABBR_DAYNAMES[Date.new(2020, 1, 1).wday] # => "Wed" Date.commercial(2020, 1, 1).to_s # => "2019-12-30" Date.commercial(2020, 1, 7).to_s # => "2020-01-05"
See argument start.
Related: Date.jd, Date.new, Date.ordinal.