Creates a new name for an existing file using a hard link. Will not overwrite new_name if it already exists (raising a subclass of SystemCallError). Not available on all platforms.
File.link("testfile", ".testfile") #=> 0 IO.readlines(".testfile")[0] #=> "This is line one\n"
Creates a symbolic link called new_name for the existing file old_name. Raises a NotImplemented exception on platforms that do not support symbolic links.
File.symlink("testfile", "link2test") #=> 0
Returns the name of the file referenced by the given link. Not available on all platforms.
File.symlink("testfile", "link2test") #=> 0 File.readlink("link2test") #=> "testfile"
Deletes the named files, returning the number of names passed as arguments. Raises an exception on any error. Since the underlying implementation relies on the unlink(2) system call, the type of exception raised depends on its error type (see linux.die.net/man/2/unlink) and has the form of e.g. Errno::ENOENT.
See also Dir::rmdir.
Splits the given string into a directory and a file component and returns them in a two-element array. See also File::dirname and File::basename.
File.split("/home/gumby/.profile") #=> ["/home/gumby", ".profile"]
Returns true if filepath points to a symbolic link, false otherwise:
symlink = File.symlink('t.txt', 'symlink') File.symlink?('symlink') # => true File.symlink?('t.txt') # => false
Returns true if the named files are identical.
file_1 and file_2 can be an IO object.
open("a", "w") {} p File.identical?("a", "a") #=> true p File.identical?("a", "./a") #=> true File.link("a", "b") p File.identical?("a", "b") #=> true File.symlink("a", "c") p File.identical?("a", "c") #=> true open("d", "w") {} p File.identical?("a", "d") #=> false
Returns the list of loaded encodings.
Encoding.list #=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>, #<Encoding:ISO-2022-JP (dummy)>] Encoding.find("US-ASCII") #=> #<Encoding:US-ASCII> Encoding.list #=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>, #<Encoding:US-ASCII>, #<Encoding:ISO-2022-JP (dummy)>]
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"}
Creates an infinite enumerator from any block, just called over and over. The result of the previous iteration is passed to the next one. If initial is provided, it is passed to the first iteration, and becomes the first element of the enumerator; if it is not provided, the first iteration receives nil, and its result becomes the first element of the iterator.
Raising StopIteration from the block stops an iteration.
Enumerator.produce(1, &:succ) # => enumerator of 1, 2, 3, 4, .... Enumerator.produce { rand(10) } # => infinite random number sequence ancestors = Enumerator.produce(node) { |prev| node = prev.parent or raise StopIteration } enclosing_section = ancestors.find { |n| n.type == :section }
Using ::produce together with Enumerable methods like Enumerable#detect, Enumerable#slice_after, Enumerable#take_while can provide Enumerator-based alternatives for while and until cycles:
# Find next Tuesday require "date" Enumerator.produce(Date.today, &:succ).detect(&:tuesday?) # Simple lexer: require "strscan" scanner = StringScanner.new("7+38/6") PATTERN = %r{\d+|[-/+*]} Enumerator.produce { scanner.scan(PATTERN) }.slice_after { scanner.eos? }.first # => ["7", "+", "38", "/", "6"]
With no argument, or if the argument is the same as the receiver, return the receiver. Otherwise, create a new exception object of the same class as the receiver, but with a message equal to string.to_str.
With no argument, or if the argument is the same as the receiver, return the receiver. Otherwise, create a new exception object of the same class as the receiver, but with a message equal to string.to_str.
Returns any backtrace associated with the exception. The backtrace is an array of strings, each containing either “filename:lineNo: in ‘method”’ or “filename:lineNo.”
def a raise "boom" end def b a() end begin b() rescue => detail print detail.backtrace.join("\n") end
produces:
prog.rb:2:in `a' prog.rb:6:in `b' prog.rb:10
In the case no backtrace has been set, nil is returned
ex = StandardError.new ex.backtrace #=> nil
Returns true if exiting successful, false if not.
Return the receiver associated with this KeyError exception.
Return the receiver associated with this NameError exception.
Return the receiver associated with this FrozenError exception.
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]
Limit the number of significant digits in newly created BigDecimal numbers to the specified value. Rounding is performed as necessary, as specified by BigDecimal.mode.
A limit of 0, the default, means no upper limit.
The limit specified by this method takes less priority over any limit specified to instance methods such as ceil, floor, truncate, or round.
Splits a BigDecimal number into four parts, returned as an array of values.
The first value represents the sign of the BigDecimal, and is -1 or 1, or 0 if the BigDecimal is Not a Number.
The second value is a string representing the significant digits of the BigDecimal, with no leading zeros.
The third value is the base used for arithmetic (currently always 10) as an Integer.
The fourth value is an Integer exponent.
If the BigDecimal can be represented as 0.xxxxxx*10**n, then xxxxxx is the string of significant digits with no leading zeros, and n is the exponent.
From these values, you can translate a BigDecimal to a float as follows:
sign, significant_digits, base, exponent = a.split f = sign * "0.#{significant_digits}".to_f * (base ** exponent)
(Note that the to_f method is provided as a more convenient way to translate a BigDecimal to a Float.)
Return the smallest integer greater than or equal to the value, as a BigDecimal.
BigDecimal('3.14159').ceil #=> 4 BigDecimal('-9.1').ceil #=> -9
If n is specified and positive, the fractional part of the result has no more than that many digits.
If n is specified and negative, at least that many digits to the left of the decimal point will be 0 in the result.
BigDecimal('3.14159').ceil(3) #=> 3.142 BigDecimal('13345.234').ceil(-2) #=> 13400.0
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 smallest number greater than or equal to rat with a precision of ndigits decimal digits (default: 0).
When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.
Returns a rational when ndigits is positive, otherwise returns an integer.
Rational(3).ceil #=> 3 Rational(2, 3).ceil #=> 1 Rational(-3, 2).ceil #=> -1 # decimal - 1 2 3 . 4 5 6 # ^ ^ ^ ^ ^ ^ # precision -3 -2 -1 0 +1 +2 Rational('-123.456').ceil(+1).to_f #=> -123.4 Rational('-123.456').ceil(-1) #=> -120
Returns a simpler approximation of the value if the optional argument eps is given (rat-|eps| <= result <= rat+|eps|), self otherwise.
r = Rational(5033165, 16777216) r.rationalize #=> (5033165/16777216) r.rationalize(Rational('0.01')) #=> (3/10) r.rationalize(Rational('0.1')) #=> (1/3)