Results for: "uniq"

StringIO#ungetbyte

Pushes back (“unshifts”) an 8-bit byte onto the stream; see Byte IO.

StringIO#truncate

Truncates the buffer string to at most integer bytes. The stream must be opened for writing.

StringScanner#unscan

Sets the [position] to its value previous to the recent successful [match] attempt:

scanner = StringScanner.new('foobarbaz')
scanner.scan(/foo/)
put_situation(scanner)
# Situation:
#   pos:       3
#   charpos:   3
#   rest:      "barbaz"
#   rest_size: 6
scanner.unscan
# => #<StringScanner 0/9 @ "fooba...">
put_situation(scanner)
# Situation:
#   pos:       0
#   charpos:   0
#   rest:      "foobarbaz"
#   rest_size: 9

Raises an exception if match values are clear:

scanner.scan(/nope/)           # => nil
match_values_cleared?(scanner) # => true
scanner.unscan                 # Raises StringScanner::Error.

ERB#run

Generate results and print them. (see ERB#result)

Tempfile#unlink

Unlinks (deletes) the file from the filesystem. One should always unlink the file after using it, as is explained in the “Explicit close” good practice section in the Tempfile overview:

file = Tempfile.new('foo')
begin
   # ...do something with file...
ensure
   file.close
   file.unlink   # deletes the temp file
end

Unlink-before-close

On POSIX systems it’s possible to unlink a file before closing it. This practice is explained in detail in the Tempfile overview (section “Unlink after creation”); please refer there for more information.

However, unlink-before-close may not be supported on non-POSIX operating systems. Microsoft Windows is the most notable case: unlinking a non-closed file will result in an error, which this method will silently ignore. If you want to practice unlink-before-close whenever possible, then you should write code like this:

file = Tempfile.new('foo')
file.unlink   # On Windows this silently fails.
begin
   # ... do something with file ...
ensure
   file.close!   # Closes the file handle. If the file wasn't unlinked
                 # because #unlink failed, then this method will attempt
                 # to do so again.
end

Method#unbind

Dissociates meth from its current receiver. The resulting UnboundMethod can subsequently be bound to a new object of the same class (see UnboundMethod).

Ractor::count

Returns the number of Ractors currently running or blocking (waiting).

Ractor.count                   #=> 1
r = Ractor.new(name: 'example') { Ractor.yield(1) }
Ractor.count                   #=> 2 (main + example ractor)
r.take                         # wait for Ractor.yield(1)
r.take                         # wait until r will finish
Ractor.count                   #=> 1

Thread#run

Wakes up thr, making it eligible for scheduling.

a = Thread.new { puts "a"; Thread.stop; puts "c" }
sleep 0.1 while a.status!='sleep'
puts "Got here"
a.run
a.join

This will produce:

a
Got here
c

Enumerable#count

Returns the count of elements, based on an argument or block criterion, if given.

With no argument and no block given, returns the number of elements:

[0, 1, 2].count                # => 3
{foo: 0, bar: 1, baz: 2}.count # => 3

With argument object given, returns the number of elements that are == to object:

[0, 1, 2, 1].count(1)           # => 2

With a block given, calls the block with each element and returns the number of elements for which the block returns a truthy value:

[0, 1, 2, 3].count {|element| element < 2}              # => 2
{foo: 0, bar: 1, baz: 2}.count {|key, value| value < 2} # => 2

Enumerable#chunk

Each element in the returned enumerator is a 2-element array consisting of:

A value returned by the block.
An array (“chunk”) containing the element for which that value was returned, and all following elements for which the block returned the same value:

So that:

Each block return value that is different from its predecessor begins a new chunk.
Each block return value that is the same as its predecessor continues the same chunk.

Example:

e = (0..10).chunk {|i| (i / 3).floor } # => #<Enumerator: ...>
# The enumerator elements.
e.next # => [0, [0, 1, 2]]
e.next # => [1, [3, 4, 5]]
e.next # => [2, [6, 7, 8]]
e.next # => [3, [9, 10]]

Method chunk is especially useful for an enumerable that is already sorted. This example counts words for each initial letter in a large array of words:

# Get sorted words from a web page.
url = 'https://raw.githubusercontent.com/eneko/data-repository/master/data/words.txt'
words = URI::open(url).readlines
# Make chunks, one for each letter.
e = words.chunk {|word| word.upcase[0] } # => #<Enumerator: ...>
# Display 'A' through 'F'.
e.each {|c, words| p [c, words.length]; break if c == 'F' }

Output:

["A", 17096]
["B", 11070]
["C", 19901]
["D", 10896]
["E", 8736]
["F", 6860]

You can use the special symbol :_alone to force an element into its own separate chuck:

a = [0, 0, 1, 1]
e = a.chunk{|i| i.even? ? :_alone : true }
e.to_a # => [[:_alone, [0]], [:_alone, [0]], [true, [1, 1]]]

For example, you can put each line that contains a URL into its own chunk:

pattern = /http/
open(filename) { |f|
  f.chunk { |line| line =~ pattern ? :_alone : true }.each { |key, lines|
    pp lines
  }
}

You can use the special symbol :_separator or nil to force an element to be ignored (not included in any chunk):

a = [0, 0, -1, 1, 1]
e = a.chunk{|i| i < 0 ? :_separator : true }
e.to_a # => [[true, [0, 0]], [true, [1, 1]]]

Note that the separator does end the chunk:

a = [0, 0, -1, 1, -1, 1]
e = a.chunk{|i| i < 0 ? :_separator : true }
e.to_a # => [[true, [0, 0]], [true, [1]], [true, [1]]]

For example, the sequence of hyphens in svn log can be eliminated as follows:

sep = "-"*72 + "\n"
IO.popen("svn log README") { |f|
  f.chunk { |line|
    line != sep || nil
  }.each { |_, lines|
    pp lines
  }
}
#=> ["r20018 | knu | 2008-10-29 13:20:42 +0900 (Wed, 29 Oct 2008) | 2 lines\n",
#    "\n",
#    "* README, README.ja: Update the portability section.\n",
#    "\n"]
#   ["r16725 | knu | 2008-05-31 23:34:23 +0900 (Sat, 31 May 2008) | 2 lines\n",
#    "\n",
#    "* README, README.ja: Add a note about default C flags.\n",
#    "\n"]
#   ...

Paragraphs separated by empty lines can be parsed as follows:

File.foreach("README").chunk { |line|
  /\A\s*\z/ !~ line || nil
}.each { |_, lines|
  pp lines
}

Etc::uname

Returns the system information obtained by uname system call.

The return value is a hash which has 5 keys at least:

:sysname, :nodename, :release, :version, :machine

Example:

require 'etc'
require 'pp'

pp Etc.uname
#=> {:sysname=>"Linux",
#    :nodename=>"boron",
#    :release=>"2.6.18-6-xen-686",
#    :version=>"#1 SMP Thu Nov 5 19:54:42 UTC 2009",
#    :machine=>"i686"}

MonitorMixin#synchronize

No documentation available

Zlib::gunzip

Decode the given gzipped string.

This method is almost equivalent to the following code:

def gunzip(string)
  sio = StringIO.new(string)
  gz = Zlib::GzipReader.new(sio, encoding: Encoding::ASCII_8BIT)
  gz.read
ensure
  gz&.close
end

GC::count

Returns the number of times GC has occurred since the process started.

Find#prune

Skips the current file or directory, restarting the loop with the next entry. If the current file is a directory, that directory will not be recursively entered. Meaningful only within the block associated with Find::find.

See the Find module documentation for an example.

Find::prune

Skips the current file or directory, restarting the loop with the next entry. If the current file is a directory, that directory will not be recursively entered. Meaningful only within the block associated with Find::find.

See the Find module documentation for an example.

Process::initgroups

Sets the supplemental group access list; the new list includes:

The group IDs of those groups to which the user given by username belongs.
The group ID gid.

Example:

Process.groups                # => [0, 1, 2, 3, 4, 6, 10, 11, 20, 26, 27]
Process.initgroups('me', 30)  # => [30, 6, 10, 11]
Process.groups                # => [30, 6, 10, 11]

Not available on all platforms.