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class method

CSV.instance

instance(string, **options)

instance(io = $stdout, **options)

instance(string, **options) {|csv| ... }

instance(io = $stdout, **options) {|csv| ... }

# File tmp/rubies/ruby-3.0.5/lib/csv.rb, line 981
def instance(data = $stdout, **options)
  # create a _signature_ for this method call, data object and options
  sig = [data.object_id] +
        options.values_at(*DEFAULT_OPTIONS.keys.sort_by { |sym| sym.to_s })

  # fetch or create the instance for this signature
  @@instances ||= Hash.new
  instance = (@@instances[sig] ||= new(data, **options))

  if block_given?
    yield instance  # run block, if given, returning result
  else
    instance        # or return the instance
  end
end

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

With no block given, returns a CSV object.

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

Example

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

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

Example

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.

Example

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

All the cached objects remains available:

Example

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:

Example

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

See also .generate_line .new .generate .open also in 3.3 · 3.2 · 3.1

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