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Contents
# frozen_string_literal: true
module Zizia
##
# A message stream that formats a message before forwarding it to an
# underlying {#stream} (STDOUT by default). Messages are formatted using
# the `#%` method; the formatter can be a string format specification like
# "Message received: %s".
#
# @example Using a simple formatter
# formatter = "Message received: %s\n"
# stream = Zizia::FormattedMessageStream.new(formatter: formatter)
#
# stream << "a message"
# # Message received: a message
# # => #<IO:<STDOUT>>
#
# @example A more complex formatter use case
# class MyFormatter
# def %(arg)
# "#{Time.now}: %s\n" % arg
# end
# end
#
# formatter = MyFormatter.new
# stream = Zizia::FormattedMessageStream.new(formatter: formatter)
#
# stream << 'a message'
# # 2018-02-02 16:10:52 -0800: a message
# # => #<IO:<STDOUT>>
#
# stream << 'another message'
# # 2018-02-02 16:10:55 -0800: another message
# # => #<IO:<STDOUT>>
#
class FormattedMessageStream
##
# @!attribute [rw] formatter
# @return [#%] A format specification
# @see https://ruby-doc.org/core-2.4.0/String.html#method-i-25
# @!attribute [rw] stream
# @return [#<<] an underlying stream to forward messages to after
# formatting
attr_accessor :formatter, :stream
##
# @param formatter [#%] A format specification
# @param stream [#<<] an underlying stream to forward messages to after
# formatting
#
# @see https://ruby-doc.org/core-2.4.0/String.html#method-i-25
def initialize(stream: STDOUT, formatter: "%s\n")
self.formatter = formatter
self.stream = stream
end
##
def <<(msg)
stream << format_message(msg)
end
##
# @param msg [#to_s]
#
# @return [String] the input, cast to a string and formatted using
def format_message(msg)
formatter % msg
end
end
end
Version data entries
11 entries across 11 versions & 1 rubygems