module Kernel - activesupport-4.2.4 Documentation

# module Kernel

### Public Instance Methods

breakpoint()
Alias for: debugger
capture(stream) { || ... } click to toggle 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 lib/active_support/core_ext/kernel/reporting.rb, line 89
    def capture(stream)
      ActiveSupport::Deprecation.warn(
        "`#capture(stream)` is deprecated and will be removed in the next release."
      ) #not thread-safe
      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) 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 3
    def class_eval(*args, &block)
      singleton_class.class_eval(*args, &block)
    end

concern(topic, &module_definition) click to toggle source

A shortcut to define a toplevel concern, not within a module.

See Module::Concerning for more.

    # File lib/active_support/core_ext/kernel/concern.rb, line 7
    def concern(topic, &module_definition)
      Object.concern topic, &module_definition
    end

debugger() click to toggle source

Starts a debugging session if the `debugger` gem 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 the debugger gem is listed in Gemfile/installed as gem): Start server with --debugger to enable *****\n"
      defined?(Rails.logger) ? 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 20
    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' }

This method is not thread-safe.

    # File lib/active_support/core_ext/kernel/reporting.rb, line 115
    def quietly
      ActiveSupport::Deprecation.warn(
        "`#quietly` is deprecated and will be removed in the next release."
      ) #not thread-safe
      silence_stream(STDOUT) do
        silence_stream(STDERR) do
          yield
        end
      end
    end

silence(stream)
Alias for: capture
silence_stream(stream) { || ... } click to toggle source

Deprecated : this method is not thread safe Silences any stream for the duration of the block.

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

    puts 'But this will'

This method is not thread-safe.

    # File lib/active_support/core_ext/kernel/reporting.rb, line 51
    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() { || ... } 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 14
    def silence_warnings
      with_warnings(nil) { yield }
    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 69
    def suppress(*exception_classes)
      yield
    rescue *exception_classes
    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 26
    def with_warnings(flag)
      old_verbose, $VERBOSE = $VERBOSE, flag
      yield
    ensure
      $VERBOSE = old_verbose
    end