Results for: "slice"

Returns the current line number of ARGF as a whole. This value can be set manually with ARGF.lineno=.

For example:

ARGF.lineno   #=> 0
ARGF.readline #=> "This is line 1\n"
ARGF.lineno   #=> 1

Sets the line number of ARGF as a whole to the given Integer.

ARGF sets the line number automatically as you read data, so normally you will not need to set it explicitly. To access the current line number use ARGF.lineno.

For example:

ARGF.lineno      #=> 0
ARGF.readline    #=> "This is line 1\n"
ARGF.lineno      #=> 1
ARGF.lineno = 0  #=> 0
ARGF.lineno      #=> 0

Creates or retrieves cached CSV objects. For arguments and options, see CSV.new.

This API is not Ractor-safe.

With no block given, returns a CSV object.

The first call to instance creates and caches a CSV object:

s0 = 's0'
csv0 = CSV.instance(s0)
csv0.class # => CSV

Subsequent calls to instance with that same string or io retrieve that same cached object:

csv1 = CSV.instance(s0)
csv1.class # => CSV
csv1.equal?(csv0) # => true # Same CSV object

A subsequent call to instance with a different string or io creates and caches a different CSV object.

s1 = 's1'
csv2 = CSV.instance(s1)
csv2.equal?(csv0) # => false # Different CSV object

All the cached objects remains available:

csv3 = CSV.instance(s0)
csv3.equal?(csv0) # true # Same CSV object
csv4 = CSV.instance(s1)
csv4.equal?(csv2) # true # Same CSV object

When a block is given, calls the block with the created or retrieved CSV object; returns the block’s return value:

CSV.instance(s0) {|csv| :foo } # => :foo

Alias for CSV.read.

Returns the count of the rows parsed or generated.

Parsing:

string = "foo,0\nbar,1\nbaz,2\n"
path = 't.csv'
File.write(path, string)
CSV.open(path) do |csv|
  csv.each do |row|
    p [csv.lineno, row]
  end
end

Output:

[1, ["foo", "0"]]
[2, ["bar", "1"]]
[3, ["baz", "2"]]

Generating:

CSV.generate do |csv|
  p csv.lineno; csv << ['foo', 0]
  p csv.lineno; csv << ['bar', 1]
  p csv.lineno; csv << ['baz', 2]
end

Output:

0
1
2

Returns the line most recently read:

string = "foo,0\nbar,1\nbaz,2\n"
path = 't.csv'
File.write(path, string)
CSV.open(path) do |csv|
  csv.each do |row|
    p [csv.lineno, csv.line]
  end
end

Output:

[1, "foo,0\n"]
[2, "bar,1\n"]
[3, "baz,2\n"]

Returns the bound receiver of the binding object.

Directs to accept specified class t. The argument string is passed to the block in which it should be converted to the desired class.

t

Argument class specifier, any object including Class.

pat

Pattern for argument, defaults to t if it responds to match.

accept(t, pat, &block)

See accept.

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

Returns the bound receiver of the method object.

(1..3).method(:map).receiver # => 1..3

Receive an incoming message from the current Ractor’s incoming port’s queue, which was sent there by send.

r = Ractor.new do
  v1 = Ractor.receive
  puts "Received: #{v1}"
end
r.send('message1')
r.take
# Here will be printed: "Received: message1"

Alternatively, private instance method receive may be used:

r = Ractor.new do
  v1 = receive
  puts "Received: #{v1}"
end
r.send('message1')
r.take
# Here will be printed: "Received: message1"

The method blocks if the queue is empty.

r = Ractor.new do
  puts "Before first receive"
  v1 = Ractor.receive
  puts "Received: #{v1}"
  v2 = Ractor.receive
  puts "Received: #{v2}"
end
wait
puts "Still not received"
r.send('message1')
wait
puts "Still received only one"
r.send('message2')
r.take

Output:

Before first receive
Still not received
Received: message1
Still received only one
Received: message2

If close_incoming was called on the ractor, the method raises Ractor::ClosedError if there are no more messages in incoming queue:

Ractor.new do
  close_incoming
  receive
end
wait
# in `receive': The incoming port is already closed => #<Ractor:#2 test.rb:1 running> (Ractor::ClosedError)

same as Ractor.receive

Returns an array of all existing Thread objects that belong to this group.

ThreadGroup::Default.list   #=> [#<Thread:0x401bdf4c run>]

Returns an array of Thread objects for all threads that are either runnable or stopped.

Thread.new { sleep(200) }
Thread.new { 1000000.times {|i| i*i } }
Thread.new { Thread.stop }
Thread.list.each {|t| p t}

This will produce:

#<Thread:0x401b3e84 sleep>
#<Thread:0x401b3f38 run>
#<Thread:0x401b3fb0 sleep>
#<Thread:0x401bdf4c run>

Returns true if thr is running or sleeping.

thr = Thread.new { }
thr.join                #=> #<Thread:0x401b3fb0 dead>
Thread.current.alive?   #=> true
thr.alive?              #=> false

See also stop? and status.

Returns the current backtrace of the target thread.

A convenience method for TracePoint.new, that activates the trace automatically.

trace = TracePoint.trace(:call) { |tp| [tp.lineno, tp.event] }
#=> #<TracePoint:enabled>

trace.enabled? #=> true

Line number of the event

Equivalent to method Kernel#gets, except that it raises an exception if called at end-of-stream:

$ cat t.txt | ruby -e "p readlines; readline"
["First line\n", "Second line\n", "\n", "Fourth line\n", "Fifth line\n"]
in `readline': end of file reached (EOFError)

Optional keyword argument chomp specifies whether line separators are to be omitted.

Returns an array containing the lines returned by calling Kernel#gets until the end-of-stream is reached; (see Line IO).

With only string argument sep given, returns the remaining lines as determined by line separator sep, or nil if none; see Line Separator:

# Default separator.
$ cat t.txt | ruby -e "p readlines"
["First line\n", "Second line\n", "\n", "Fourth line\n", "Fifth line\n"]

# Specified separator.
$ cat t.txt | ruby -e "p readlines 'li'"
["First li", "ne\nSecond li", "ne\n\nFourth li", "ne\nFifth li", "ne\n"]

# Get-all separator.
$ cat t.txt | ruby -e "p readlines nil"
["First line\nSecond line\n\nFourth line\nFifth line\n"]

# Get-paragraph separator.
$ cat t.txt | ruby -e "p readlines ''"
["First line\nSecond line\n\n", "Fourth line\nFifth line\n"]

With only integer argument limit given, limits the number of bytes in the line; see Line Limit:

$cat t.txt | ruby -e "p readlines 10"
["First line", "\n", "Second lin", "e\n", "\n", "Fourth lin", "e\n", "Fifth line", "\n"]

$cat t.txt | ruby -e "p readlines 11"
["First line\n", "Second line", "\n", "\n", "Fourth line", "\n", "Fifth line\n"]

$cat t.txt | ruby -e "p readlines 12"
["First line\n", "Second line\n", "\n", "Fourth line\n", "Fifth line\n"]

With arguments sep and limit given, combines the two behaviors; see Line Separator and Line Limit.

Optional keyword argument chomp specifies whether line separators are to be omitted:

$ cat t.txt | ruby -e "p readlines(chomp: true)"
["First line", "Second line", "", "Fourth line", "Fifth line"]

Optional keyword arguments enc_opts specify encoding options; see Encoding options.

Suspends the current thread for duration seconds (which may be any number, including a Float with fractional seconds). Returns the actual number of seconds slept (rounded), which may be less than that asked for if another thread calls Thread#run. Called without an argument, sleep() will sleep forever.

Time.new    #=> 2008-03-08 19:56:19 +0900
sleep 1.2   #=> 1
Time.new    #=> 2008-03-08 19:56:20 +0900
sleep 1.9   #=> 2
Time.new    #=> 2008-03-08 19:56:22 +0900

Returns an object formed from operands via either:

• A method named by symbol.

• A block to which each operand is passed.

With method-name argument symbol, combines operands using the method:

# Sum, without initial_operand.
(1..4).inject(:+)     # => 10
# Sum, with initial_operand.
(1..4).inject(10, :+) # => 20

With a block, passes each operand to the block:

# Sum of squares, without initial_operand.
(1..4).inject {|sum, n| sum + n*n }    # => 30
# Sum of squares, with initial_operand.
(1..4).inject(2) {|sum, n| sum + n*n } # => 32

Operands

If argument initial_operand is not given, the operands for inject are simply the elements of self. Example calls and their operands:

• (1..4).inject(:+)

  [1, 2, 3, 4].

• (1...4).inject(:+)

  [1, 2, 3].

• ('a'..'d').inject(:+)

  ['a', 'b', 'c', 'd'].

• ('a'...'d').inject(:+)

  ['a', 'b', 'c'].

Examples with first operand (which is self.first) of various types:

# Integer.
(1..4).inject(:+)                # => 10
# Float.
[1.0, 2, 3, 4].inject(:+)        # => 10.0
# Character.
('a'..'d').inject(:+)            # => "abcd"
# Complex.
[Complex(1, 2), 3, 4].inject(:+) # => (8+2i)

If argument initial_operand is given, the operands for inject are that value plus the elements of self. Example calls their operands:

• (1..4).inject(10, :+)

  [10, 1, 2, 3, 4].

• (1...4).inject(10, :+)

  [10, 1, 2, 3].

• ('a'..'d').inject('e', :+)

  ['e', 'a', 'b', 'c', 'd'].

• ('a'...'d').inject('e', :+)

  ['e', 'a', 'b', 'c'].

Examples with initial_operand of various types:

# Integer.
(1..4).inject(2, :+)               # => 12
# Float.
(1..4).inject(2.0, :+)             # => 12.0
# String.
('a'..'d').inject('foo', :+)       # => "fooabcd"
# Array.
%w[a b c].inject(['x'], :push)     # => ["x", "a", "b", "c"]
# Complex.
(1..4).inject(Complex(2, 2), :+)   # => (12+2i)

Combination by Given Method

If the method-name argument symbol is given, the operands are combined by that method:

• The first and second operands are combined.

• That result is combined with the third operand.

• That result is combined with the fourth operand.

• And so on.

The return value from inject is the result of the last combination.

This call to inject computes the sum of the operands:

(1..4).inject(:+) # => 10

Examples with various methods:

# Integer addition.
(1..4).inject(:+)                # => 10
# Integer multiplication.
(1..4).inject(:*)                # => 24
# Character range concatenation.
('a'..'d').inject('', :+)        # => "abcd"
# String array concatenation.
%w[foo bar baz].inject('', :+)   # => "foobarbaz"
# Hash update.
h = [{foo: 0, bar: 1}, {baz: 2}, {bat: 3}].inject(:update)
h # => {:foo=>0, :bar=>1, :baz=>2, :bat=>3}
# Hash conversion to nested arrays.
h = {foo: 0, bar: 1}.inject([], :push)
h # => [[:foo, 0], [:bar, 1]]

Combination by Given Block

If a block is given, the operands are passed to the block:

• The first call passes the first and second operands.

• The second call passes the result of the first call, along with the third operand.

• The third call passes the result of the second call, along with the fourth operand.

• And so on.

The return value from inject is the return value from the last block call.

This call to inject gives a block that writes the memo and element, and also sums the elements:

(1..4).inject do |memo, element|
  p "Memo: #{memo}; element: #{element}"
  memo + element
end # => 10

Output:

"Memo: 1; element: 2"
"Memo: 3; element: 3"
"Memo: 6; element: 4"

Enumerable#reduce is an alias for Enumerable#inject.