Kernel

breakpoint()

capture(stream)

Captures the given stream and returns it:

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

Also aliased as: silence

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 68
def capture(stream)
  begin
    stream = stream.to_s
    eval "$#{stream} = StringIO.new"
    yield
    result = eval("$#{stream}").string
  ensure
    eval("$#{stream} = #{stream.upcase}")
  end

  result
end

class_eval(*args, &block)

#class_eval on an object acts like singleton_class.class_eval.

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/singleton_class.rb, line 10
def class_eval(*args, &block)
  singleton_class.class_eval(*args, &block)
end

debugger()

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

Also aliased as: breakpoint

Source: show | on GitHub

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

enable_warnings()

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

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 15
def enable_warnings
  with_warnings(true) { yield }
end

quietly()

Silences both STDOUT and STDERR, even for subprocesses.

quietly { system 'bundle install' }

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 86
def quietly
  silence_stream(STDOUT) do
    silence_stream(STDERR) do
      yield
    end
  end
end

silence(stream)

silence_stream(stream)

Silences any stream for the duration of the block.

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

puts 'But this will'

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 39
def silence_stream(stream)
  old_stream = stream.dup
  stream.reopen(RbConfig::CONFIG['host_os'] =~ %rmswin|mingw/ ? 'NUL:' : '/dev/null')
  stream.sync = true
  yield
ensure
  stream.reopen(old_stream)
end

silence_warnings()

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

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 10
def silence_warnings
  with_warnings(nil) { yield }
end

singleton_class()

Returns the object’s singleton class.

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/singleton_class.rb, line 3
def singleton_class
  class << self
    self
  end
end

suppress(*exception_classes)

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"

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 56
def suppress(*exception_classes)
  begin yield
  rescue Exception => e
    raise unless exception_classes.any? { |cls| e.kind_of?(cls) }
  end
end

with_warnings(flag)

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

Source: show | on GitHub

# File activesupport/lib/active_support/core_ext/kernel/reporting.rb, line 20
def with_warnings(flag)
  old_verbose, $VERBOSE = $VERBOSE, flag
  yield
ensure
  $VERBOSE = old_verbose
end

Module Kernel