module Kernel

Public Instance Methods

breakpoint()

Alias for: debugger

capture(stream) { || ... } Show source

Captures the given stream and returns it:

stream = capture(:stdout) { puts 'notice' }
stream # => "notice\n"

stream = capture(:stderr) { warn 'error' }
stream # => "error\n"

even for subprocesses:

stream = capture(:stdout) { system('echo notice') }
stream # => "notice\n"

stream = capture(:stderr) { system('echo error 1>&2') }
stream # => "error\n"

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 82
def capture(stream)
  stream = stream.to_s
  captured_stream = Tempfile.new(stream)
  stream_io = eval("$#{stream}")
  origin_stream = stream_io.dup
  stream_io.reopen(captured_stream)

  yield

  stream_io.rewind
  return captured_stream.read
ensure
  captured_stream.close
  captured_stream.unlink
  stream_io.reopen(origin_stream)
end

Also aliased as: silence

class_eval(*args, &block) Show source

#class_eval on an object acts like singleton_class.class_eval.

# File activesupport/lib/active_support/core_ext/kernel/singleton_class.rb, line 3
def class_eval(*args, &block)
  singleton_class.class_eval(*args, &block)
end

debugger() Show source

Starts a debugging session if the debugger gem has been loaded (call rails server –debugger to do load it).

# File activesupport/lib/active_support/core_ext/kernel/debugger.rb, line 4
def debugger
  message = "\n***** Debugger requested, but was not available (ensure the debugger gem is listed in Gemfile/installed as gem): Start server with --debugger to enable *****\n"
  defined?(Rails) ? Rails.logger.info(message) : $stderr.puts(message)
end

Also aliased as: breakpoint

enable_warnings() { || ... } Show source

Sets $VERBOSE to true for the duration of the block and back to its original value afterwards.

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 19
def enable_warnings
  with_warnings(true) { yield }
end

quietly() { || ... } Show source

Silences both STDOUT and STDERR, even for subprocesses.

quietly { system 'bundle install' }

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 103
def quietly
  silence_stream(STDOUT) do
    silence_stream(STDERR) do
      yield
    end
  end
end

silence(stream)

Alias for: capture

silence_stream(stream) { || ... } Show source

Silences any stream for the duration of the block.

silence_stream(STDOUT) do
  puts 'This will never be seen'
end

puts 'But this will'

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 44
def silence_stream(stream)
  old_stream = stream.dup
  stream.reopen(RbConfig::CONFIG['host_os'] =~ /mswin|mingw/ ? 'NUL:' : '/dev/null')
  stream.sync = true
  yield
ensure
  stream.reopen(old_stream)
  old_stream.close
end

silence_warnings() { || ... } Show source

Sets $VERBOSE to nil for the duration of the block and back to its original value afterwards.

silence_warnings do
  value = noisy_call # no warning voiced
end

noisy_call # warning voiced

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 13
def silence_warnings
  with_warnings(nil) { yield }
end

suppress(*exception_classes) { || ... } Show source

Blocks and ignores any exception passed as argument if raised within the block.

suppress(ZeroDivisionError) do
  1/0
  puts 'This code is NOT reached'
end

puts 'This code gets executed and nothing related to ZeroDivisionError was seen'

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 62
def suppress(*exception_classes)
  yield
rescue *exception_classes
end

with_warnings(flag) { || ... } Show source

Sets $VERBOSE for the duration of the block and back to its original value afterwards.

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 25
def with_warnings(flag)
  old_verbose, $VERBOSE = $VERBOSE, flag
  yield
ensure
  $VERBOSE = old_verbose
end