Module: Kernel

Defined in:
activesupport/lib/active_support/core_ext/kernel/debugger.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

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

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"



82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
 
# 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

#class_eval(*args, &block) ⇒ Object

class_eval on an object acts like singleton_class.class_eval.



3
4
5
 
# 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 ⇒ Object Also known as: breakpoint

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



4
5
6
7
 
# 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

#enable_warnings ⇒ Object

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



19
20
21
 
# File 'activesupport/lib/active_support/core_ext/kernel/reporting.rb', line 19

def enable_warnings
  with_warnings(true) { yield }
end

#quietly ⇒ Object

Silences both STDOUT and STDERR, even for subprocesses.

quietly { system 'bundle install' }



103
104
105
106
107
108
109
 
# 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_stderr ⇒ Object

For compatibility



33
34
35
 
# File 'activesupport/lib/active_support/core_ext/kernel/reporting.rb', line 33

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'



44
45
46
47
48
49
50
51
52
 
# 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 ⇒ Object

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



13
14
15
 
# File 'activesupport/lib/active_support/core_ext/kernel/reporting.rb', line 13

def silence_warnings
  with_warnings(nil) { yield }
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'



62
63
64
65
 
# File 'activesupport/lib/active_support/core_ext/kernel/reporting.rb', line 62

def suppress(*exception_classes)
  yield
rescue *exception_classes
end

#with_warnings(flag) ⇒ Object

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



25
26
27
28
29
30
 
# 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