Yields self to the block, and then returns self. The primary purpose of this method is to “tap into” a method chain, in order to perform operations on intermediate results within the chain.
(1..10) .tap {|x| puts "original: #{x}" } .to_a .tap {|x| puts "array: #{x}" } .select {|x| x.even? } .tap {|x| puts "evens: #{x}" } .map {|x| x*x } .tap {|x| puts "squares: #{x}" }
Returns arg converted to a float. Numeric types are converted directly, and with exception to String and nil the rest are converted using arg.to_f. Converting a String with invalid characters will result in a ArgumentError. Converting nil generates a TypeError. Exceptions can be suppressed by passing exception: false.
Float(1) #=> 1.0 Float("123.456") #=> 123.456 Float("123.0_badstring") #=> ArgumentError: invalid value for Float(): "123.0_badstring" Float(nil) #=> TypeError: can't convert nil into Float Float("123.0_badstring", exception: false) #=> nil
Returns the string resulting from applying format_string to any additional arguments. Within the format string, any characters other than format sequences are copied to the result.
The syntax of a format sequence is as follows.
%[flags][width][.precision]type
A format sequence consists of a percent sign, followed by optional flags, width, and precision indicators, then terminated with a field type character. The field type controls how the corresponding sprintf argument is to be interpreted, while the flags modify that interpretation.
The field type characters are:
Field | Integer Format
------+--------------------------------------------------------------
b | Convert argument as a binary number.
| Negative numbers will be displayed as a two's complement
| prefixed with `..1'.
B | Equivalent to `b', but uses an uppercase 0B for prefix
| in the alternative format by #.
d | Convert argument as a decimal number.
i | Identical to `d'.
o | Convert argument as an octal number.
| Negative numbers will be displayed as a two's complement
| prefixed with `..7'.
u | Identical to `d'.
x | Convert argument as a hexadecimal number.
| Negative numbers will be displayed as a two's complement
| prefixed with `..f' (representing an infinite string of
| leading 'ff's).
X | Equivalent to `x', but uses uppercase letters.
Field | Float Format
------+--------------------------------------------------------------
e | Convert floating point argument into exponential notation
| with one digit before the decimal point as [-]d.dddddde[+-]dd.
| The precision specifies the number of digits after the decimal
| point (defaulting to six).
E | Equivalent to `e', but uses an uppercase E to indicate
| the exponent.
f | Convert floating point argument as [-]ddd.dddddd,
| where the precision specifies the number of digits after
| the decimal point.
g | Convert a floating point number using exponential form
| if the exponent is less than -4 or greater than or
| equal to the precision, or in dd.dddd form otherwise.
| The precision specifies the number of significant digits.
G | Equivalent to `g', but use an uppercase `E' in exponent form.
a | Convert floating point argument as [-]0xh.hhhhp[+-]dd,
| which is consisted from optional sign, "0x", fraction part
| as hexadecimal, "p", and exponential part as decimal.
A | Equivalent to `a', but use uppercase `X' and `P'.
Field | Other Format
------+--------------------------------------------------------------
c | Argument is the numeric code for a single character or
| a single character string itself.
p | The valuing of argument.inspect.
s | Argument is a string to be substituted. If the format
| sequence contains a precision, at most that many characters
| will be copied.
% | A percent sign itself will be displayed. No argument taken.
The flags modifies the behavior of the formats. The flag characters are:
Flag | Applies to | Meaning
---------+---------------+-----------------------------------------
space | bBdiouxX | Leave a space at the start of
| aAeEfgG | non-negative numbers.
| (numeric fmt) | For `o', `x', `X', `b' and `B', use
| | a minus sign with absolute value for
| | negative values.
---------+---------------+-----------------------------------------
(digit)$ | all | Specifies the absolute argument number
| | for this field. Absolute and relative
| | argument numbers cannot be mixed in a
| | sprintf string.
---------+---------------+-----------------------------------------
# | bBoxX | Use an alternative format.
| aAeEfgG | For the conversions `o', increase the precision
| | until the first digit will be `0' if
| | it is not formatted as complements.
| | For the conversions `x', `X', `b' and `B'
| | on non-zero, prefix the result with ``0x'',
| | ``0X'', ``0b'' and ``0B'', respectively.
| | For `a', `A', `e', `E', `f', `g', and 'G',
| | force a decimal point to be added,
| | even if no digits follow.
| | For `g' and 'G', do not remove trailing zeros.
---------+---------------+-----------------------------------------
+ | bBdiouxX | Add a leading plus sign to non-negative
| aAeEfgG | numbers.
| (numeric fmt) | For `o', `x', `X', `b' and `B', use
| | a minus sign with absolute value for
| | negative values.
---------+---------------+-----------------------------------------
- | all | Left-justify the result of this conversion.
---------+---------------+-----------------------------------------
0 (zero) | bBdiouxX | Pad with zeros, not spaces.
| aAeEfgG | For `o', `x', `X', `b' and `B', radix-1
| (numeric fmt) | is used for negative numbers formatted as
| | complements.
---------+---------------+-----------------------------------------
* | all | Use the next argument as the field width.
| | If negative, left-justify the result. If the
| | asterisk is followed by a number and a dollar
| | sign, use the indicated argument as the width.
Examples of flags:
# `+' and space flag specifies the sign of non-negative numbers. sprintf("%d", 123) #=> "123" sprintf("%+d", 123) #=> "+123" sprintf("% d", 123) #=> " 123" # `#' flag for `o' increases number of digits to show `0'. # `+' and space flag changes format of negative numbers. sprintf("%o", 123) #=> "173" sprintf("%#o", 123) #=> "0173" sprintf("%+o", -123) #=> "-173" sprintf("%o", -123) #=> "..7605" sprintf("%#o", -123) #=> "..7605" # `#' flag for `x' add a prefix `0x' for non-zero numbers. # `+' and space flag disables complements for negative numbers. sprintf("%x", 123) #=> "7b" sprintf("%#x", 123) #=> "0x7b" sprintf("%+x", -123) #=> "-7b" sprintf("%x", -123) #=> "..f85" sprintf("%#x", -123) #=> "0x..f85" sprintf("%#x", 0) #=> "0" # `#' for `X' uses the prefix `0X'. sprintf("%X", 123) #=> "7B" sprintf("%#X", 123) #=> "0X7B" # `#' flag for `b' add a prefix `0b' for non-zero numbers. # `+' and space flag disables complements for negative numbers. sprintf("%b", 123) #=> "1111011" sprintf("%#b", 123) #=> "0b1111011" sprintf("%+b", -123) #=> "-1111011" sprintf("%b", -123) #=> "..10000101" sprintf("%#b", -123) #=> "0b..10000101" sprintf("%#b", 0) #=> "0" # `#' for `B' uses the prefix `0B'. sprintf("%B", 123) #=> "1111011" sprintf("%#B", 123) #=> "0B1111011" # `#' for `e' forces to show the decimal point. sprintf("%.0e", 1) #=> "1e+00" sprintf("%#.0e", 1) #=> "1.e+00" # `#' for `f' forces to show the decimal point. sprintf("%.0f", 1234) #=> "1234" sprintf("%#.0f", 1234) #=> "1234." # `#' for `g' forces to show the decimal point. # It also disables stripping lowest zeros. sprintf("%g", 123.4) #=> "123.4" sprintf("%#g", 123.4) #=> "123.400" sprintf("%g", 123456) #=> "123456" sprintf("%#g", 123456) #=> "123456."
The field width is an optional integer, followed optionally by a period and a precision. The width specifies the minimum number of characters that will be written to the result for this field.
Examples of width:
# padding is done by spaces, width=20 # 0 or radix-1. <------------------> sprintf("%20d", 123) #=> " 123" sprintf("%+20d", 123) #=> " +123" sprintf("%020d", 123) #=> "00000000000000000123" sprintf("%+020d", 123) #=> "+0000000000000000123" sprintf("% 020d", 123) #=> " 0000000000000000123" sprintf("%-20d", 123) #=> "123 " sprintf("%-+20d", 123) #=> "+123 " sprintf("%- 20d", 123) #=> " 123 " sprintf("%020x", -123) #=> "..ffffffffffffffff85"
For numeric fields, the precision controls the number of decimal places displayed. For string fields, the precision determines the maximum number of characters to be copied from the string. (Thus, the format sequence %10.10s will always contribute exactly ten characters to the result.)
Examples of precisions:
# precision for `d', 'o', 'x' and 'b' is # minimum number of digits <------> sprintf("%20.8d", 123) #=> " 00000123" sprintf("%20.8o", 123) #=> " 00000173" sprintf("%20.8x", 123) #=> " 0000007b" sprintf("%20.8b", 123) #=> " 01111011" sprintf("%20.8d", -123) #=> " -00000123" sprintf("%20.8o", -123) #=> " ..777605" sprintf("%20.8x", -123) #=> " ..ffff85" sprintf("%20.8b", -11) #=> " ..110101" # "0x" and "0b" for `#x' and `#b' is not counted for # precision but "0" for `#o' is counted. <------> sprintf("%#20.8d", 123) #=> " 00000123" sprintf("%#20.8o", 123) #=> " 00000173" sprintf("%#20.8x", 123) #=> " 0x0000007b" sprintf("%#20.8b", 123) #=> " 0b01111011" sprintf("%#20.8d", -123) #=> " -00000123" sprintf("%#20.8o", -123) #=> " ..777605" sprintf("%#20.8x", -123) #=> " 0x..ffff85" sprintf("%#20.8b", -11) #=> " 0b..110101" # precision for `e' is number of # digits after the decimal point <------> sprintf("%20.8e", 1234.56789) #=> " 1.23456789e+03" # precision for `f' is number of # digits after the decimal point <------> sprintf("%20.8f", 1234.56789) #=> " 1234.56789000" # precision for `g' is number of # significant digits <-------> sprintf("%20.8g", 1234.56789) #=> " 1234.5679" # <-------> sprintf("%20.8g", 123456789) #=> " 1.2345679e+08" # precision for `s' is # maximum number of characters <------> sprintf("%20.8s", "string test") #=> " string t"
Examples:
sprintf("%d %04x", 123, 123) #=> "123 007b" sprintf("%08b '%4s'", 123, 123) #=> "01111011 ' 123'" sprintf("%1$*2$s %2$d %1$s", "hello", 8) #=> " hello 8 hello" sprintf("%1$*2$s %2$d", "hello", -8) #=> "hello -8" sprintf("%+g:% g:%-g", 1.23, 1.23, 1.23) #=> "+1.23: 1.23:1.23" sprintf("%u", -123) #=> "-123"
For more complex formatting, Ruby supports a reference by name. %<name>s style uses format style, but %{name} style doesn’t.
Examples:
sprintf("%<foo>d : %<bar>f", { :foo => 1, :bar => 2 }) #=> 1 : 2.000000 sprintf("%{foo}f", { :foo => 1 }) # => "1f"
Equivalent to Proc.new, except the resulting Proc objects check the number of parameters passed when called.
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.
Deprecated. Use block_given? instead.
catch executes its block. If throw is not called, the block executes normally, and catch returns the value of the last expression evaluated.
catch(1) { 123 } # => 123
If throw(tag2, val) is called, Ruby searches up its stack for a catch block whose tag has the same object_id as tag2. When found, the block stops executing and returns val (or nil if no second argument was given to throw).
catch(1) { throw(1, 456) } # => 456 catch(1) { throw(1) } # => nil
When tag is passed as the first argument, catch yields it as the parameter of the block.
catch(1) {|x| x + 2 } # => 3
When no tag is given, catch yields a new unique object (as from Object.new) as the block parameter. This object can then be used as the argument to throw, and will match the correct catch block.
catch do |obj_A| catch do |obj_B| throw(obj_B, 123) puts "This puts is not reached" end puts "This puts is displayed" 456 end # => 456 catch do |obj_A| catch do |obj_B| throw(obj_A, 123) puts "This puts is still not reached" end puts "Now this puts is also not reached" 456 end # => 123
Tallies the collection, i.e., counts the occurrences of each element. Returns a hash with the elements of the collection as keys and the corresponding counts as values.
["a", "b", "c", "b"].tally #=> {"a"=>1, "b"=>2, "c"=>1}
Returns first n elements from enum.
a = [1, 2, 3, 4, 5, 0] a.take(3) #=> [1, 2, 3] a.take(30) #=> [1, 2, 3, 4, 5, 0]
Enables coverage measurement.
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)
Returns self, for backward compatibility.
Compresses the given string. Valid values of level are Zlib::NO_COMPRESSION, Zlib::BEST_SPEED, Zlib::BEST_COMPRESSION, Zlib::DEFAULT_COMPRESSION, or an integer from 0 to 9.
This method is almost equivalent to the following code:
def deflate(string, level) z = Zlib::Deflate.new(level) dst = z.deflate(string, Zlib::FINISH) z.close dst end
See also Zlib.inflate
Decompresses string. Raises a Zlib::NeedDict exception if a preset dictionary is needed for decompression.
This method is almost equivalent to the following code:
def inflate(string) zstream = Zlib::Inflate.new buf = zstream.inflate(string) zstream.finish zstream.close buf end
See also Zlib.deflate
Returns true if the named file is readable by the effective user and group id of this process. See eaccess(3).
Note that some OS-level security features may cause this to return true even though the file is not readable by the effective user/group.
Returns true if the named file is writable by the effective user and group id of this process. See eaccess(3).
Note that some OS-level security features may cause this to return true even though the file is not writable by the effective user/group.
Returns true if the named file is executable by the effective user and group id of this process. See eaccess(3).
Windows does not support execute permissions separately from read permissions. On Windows, a file is only considered executable if it ends in .bat, .cmd, .com, or .exe.
Note that some OS-level security features may cause this to return true even though the file is not executable by the effective user/group.
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.
Returns the currently set formatter. By default, it is set to DidYouMean::Formatter.
Updates the primary formatter used to format the suggestions.
If src is not same as dest, copies it and changes the permission mode to mode. If dest is a directory, destination is dest/src. This method removes destination before copy.
FileUtils.install 'ruby', '/usr/local/bin/ruby', mode: 0755, verbose: true FileUtils.install 'lib.rb', '/usr/local/lib/ruby/site_ruby', verbose: true
If src is not same as dest, copies it and changes the permission mode to mode. If dest is a directory, destination is dest/src. This method removes destination before copy.
FileUtils.install 'ruby', '/usr/local/bin/ruby', mode: 0755, verbose: true FileUtils.install 'lib.rb', '/usr/local/lib/ruby/site_ruby', verbose: true