Module: Kernel

Defined in:
activesupport/lib/active_support/core_ext/kernel/debugger.rb,
activesupport/lib/active_support/core_ext/kernel/requires.rb,
activesupport/lib/active_support/core_ext/kernel/reporting.rb,
activesupport/lib/active_support/core_ext/kernel/singleton_class.rb

Instance Method Summary collapse

Instance Method Details

#breakpointObject


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# File 'activesupport/lib/active_support/core_ext/kernel/debugger.rb', line 11

def breakpoint
  message = "\n***** The 'breakpoint' command has been renamed 'debugger' -- please change *****\n"
  defined?(Rails) ? Rails.logger.info(message) : $stderr.puts(message)
  debugger
end

#capture(stream) ⇒ Object Also known as: silence

Captures the given stream and returns it:

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

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# 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) ⇒ Object

class_eval on an object acts like singleton_class.class_eval.


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# 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

#debuggerObject

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


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# 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_warningsObject

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


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# File 'activesupport/lib/active_support/core_ext/kernel/reporting.rb', line 15

def enable_warnings
  with_warnings(true) { yield }
end

#quietlyObject

Silences both STDOUT and STDERR, even for subprocesses.

quietly { system 'bundle install' }

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# 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

#require_library_or_gem(library_name) ⇒ Object

Require a library with fallback to RubyGems. Warnings during library loading are silenced to increase signal/noise for application warnings.


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# File 'activesupport/lib/active_support/core_ext/kernel/requires.rb', line 7

def require_library_or_gem(library_name)
  silence_warnings do
    begin
      require library_name
    rescue LoadError => cannot_require
      # 1. Requiring the module is unsuccessful, maybe it's a gem and nobody required rubygems yet. Try.
      begin
        require 'rubygems'
      rescue LoadError # => rubygems_not_installed
        raise cannot_require
      end
      # 2. Rubygems is installed and loaded. Try to load the library again
      begin
        require library_name
      rescue LoadError # => gem_not_installed
        raise cannot_require
      end
    end
  end
end

#silence_stderrObject

For compatibility


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# File 'activesupport/lib/active_support/core_ext/kernel/reporting.rb', line 28

def silence_stderr #:nodoc:
  silence_stream(STDERR) { yield }
end

#silence_stream(stream) ⇒ Object

Silences any stream for the duration of the block.

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

puts 'But this will'

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# 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'] =~ /mswin|mingw/ ? 'NUL:' : '/dev/null')
  stream.sync = true
  yield
ensure
  stream.reopen(old_stream)
end

#silence_warningsObject

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

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# File 'activesupport/lib/active_support/core_ext/kernel/reporting.rb', line 10

def silence_warnings
  with_warnings(nil) { yield }
end

#singleton_classObject

Returns the object's singleton class.


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# File 'activesupport/lib/active_support/core_ext/kernel/singleton_class.rb', line 3

def singleton_class
  class << self
    self
  end
end

#suppress(*exception_classes) ⇒ Object

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"

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# 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) ⇒ Object

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


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# 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