# module Kernel

### Public Instance Methods

breakpoint() click to toggle source
Alias for: debugger
capture(stream) { || ... } click to toggle source

Captures the given stream and returns it:

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

    # File 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

Also aliased as: silence
class_eval(*args, &block) click to toggle source

#class_eval on an object acts like singleton_class.class_eval.

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

debugger() click to toggle source

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

    # File 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

Also aliased as: breakpoint
enable_warnings() { || ... } click to toggle source

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

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

quietly() { || ... } click to toggle source

Silences both STDOUT and STDERR, even for subprocesses.

    quietly { system 'bundle install' }

    # File 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) click to toggle source
Alias for: capture
silence_stream(stream) { || ... } click to toggle 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 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() { || ... } click to toggle 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 lib/active_support/core_ext/kernel/reporting.rb, line 10
    def silence_warnings
      with_warnings(nil) { yield }
    end

singleton_class() click to toggle source

Returns the object’s singleton class.

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

suppress(*exception_classes) { || ... } click to toggle 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 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) { || ... } click to toggle source

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

    # File 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