Class: Pocketwatch::Watcher

Inherits:
Object
  • Object
show all
Defined in:
lib/pocketwatch/watcher.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(command, options = {}) ⇒ Watcher

Returns a new instance of Watcher.

Parameters:

  • command (String) —

    the command to run on an interval

  • options (Hash) (defaults to: {}) —

    the options hash determined by the command-line option parser



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# File 'lib/pocketwatch/watcher.rb', line 13

def initialize(command, options = {})
  @command = command

  if @command.nil? || @command.empty?
    warn "No command provided."
    exit 1
  end
  @options = options
end

Instance Attribute Details

#command ⇒ String (readonly)

Returns the command to run on an interval.

Returns:

  • (String) —

    the command to run on an interval



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# File 'lib/pocketwatch/watcher.rb', line 4

def command
  @command
end

#options ⇒ Hash (readonly)

Returns the options hash determined by the command-line option parser.

Returns:

  • (Hash) —

    the options hash determined by the command-line option parser



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# File 'lib/pocketwatch/watcher.rb', line 8

def options
  @options
end

Instance Method Details

#run ⇒ void

This method returns an undefined value.

Begin the watcher task, executing the provided command in a loop. The loop will only break when interrupted in the shell.



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# File 'lib/pocketwatch/watcher.rb', line 27

def run
  loop do
    # Double buffer the output by precomputing the results of the system
    # call. Then, clear the terminal and print the results as quickly as
    # possible - this should avoid any flickering due to clearing the
    # terminal. Restrict the output of the command to the current height of
    # the terminal - scrolling is not supported, and we want to see the
    # first part of the output, not the last.
    num_lines = `tput lines`.strip.to_i - 1
    num_lines = 1 unless num_lines.positive?
    output = `#{@command}`.split("\n").first(num_lines)

    clear_screen
    puts output

    sleep(@options[:interval] || 2)
  end
rescue Errno::EPIPE, SystemExit, Interrupt
  clear_screen
  exit 0
end