Results for: "slice"

Object#remove_instance_variable

Removes the named instance variable from obj, returning that variable’s value. The name can be passed as a symbol or as a string.

class Dummy
  attr_reader :var
  def initialize
    @var = 99
  end
  def remove
    remove_instance_variable(:@var)
  end
end
d = Dummy.new
d.var      #=> 99
d.remove   #=> 99
d.var      #=> nil

Module#protected_instance_methods

Returns a list of the protected instance methods defined in mod. If the optional parameter is false, the methods of any ancestors are not included.

Module#private_instance_methods

Returns a list of the private instance methods defined in mod. If the optional parameter is false, the methods of any ancestors are not included.

module Mod
  def method1()  end
  private :method1
  def method2()  end
end
Mod.instance_methods           #=> [:method2]
Mod.private_instance_methods   #=> [:method1]

Module#undefined_instance_methods

Returns a list of the undefined instance methods defined in mod. The undefined methods of any ancestors are not included.

Module#const_source_location

Returns the Ruby source filename and line number containing the definition of the constant specified. If the named constant is not found, nil is returned. If the constant is found, but its source location can not be extracted (constant is defined in C code), empty array is returned.

inherit specifies whether to lookup in mod.ancestors (true by default).

# test.rb:
class A         # line 1
  C1 = 1
  C2 = 2
end

module M        # line 6
  C3 = 3
end

class B < A     # line 10
  include M
  C4 = 4
end

class A # continuation of A definition
  C2 = 8 # constant redefinition; warned yet allowed
end

p B.const_source_location('C4')           # => ["test.rb", 12]
p B.const_source_location('C3')           # => ["test.rb", 7]
p B.const_source_location('C1')           # => ["test.rb", 2]

p B.const_source_location('C3', false)    # => nil  -- don't lookup in ancestors

p A.const_source_location('C2')           # => ["test.rb", 16] -- actual (last) definition place

p Object.const_source_location('B')       # => ["test.rb", 10] -- top-level constant could be looked through Object
p Object.const_source_location('A')       # => ["test.rb", 1] -- class reopening is NOT considered new definition

p B.const_source_location('A')            # => ["test.rb", 1]  -- because Object is in ancestors
p M.const_source_location('A')            # => ["test.rb", 1]  -- Object is not ancestor, but additionally checked for modules

p Object.const_source_location('A::C1')   # => ["test.rb", 2]  -- nesting is supported
p Object.const_source_location('String')  # => []  -- constant is defined in C code

Socket::ip_address_list

Returns local IP addresses as an array.

The array contains Addrinfo objects.

pp Socket.ip_address_list
#=> [#<Addrinfo: 127.0.0.1>,
     #<Addrinfo: 192.168.0.128>,
     #<Addrinfo: ::1>,
     ...]

Addrinfo#ipv6_mc_linklocal?

Returns true for IPv6 multicast link-local scope address. It returns false otherwise.

StringScanner#beginning_of_line?

Returns whether the [position] is at the beginning of a line; that is, at the beginning of the [stored string] or immediately after a newline:

scanner = StringScanner.new(MULTILINE_TEXT)
scanner.string
# => "Go placidly amid the noise and haste,\nand remember what peace there may be in silence.\n"
scanner.pos                # => 0
scanner.beginning_of_line? # => true

scanner.scan_until(/,/)    # => "Go placidly amid the noise and haste,"
scanner.beginning_of_line? # => false

scanner.scan(/\n/)         # => "\n"
scanner.beginning_of_line? # => true

scanner.terminate
scanner.beginning_of_line? # => true

scanner.concat('x')
scanner.terminate
scanner.beginning_of_line? # => false

StringScanner#bol? is an alias for StringScanner#beginning_of_line?.

WIN32OLE::ole_reference_count

Returns reference counter of Dispatch interface of WIN32OLE object. You should not use this method because this method exists only for debugging WIN32OLE.

WIN32OLE#ole_activex_initialize

Initialize WIN32OLE object(ActiveX Control) by calling IPersistMemory::InitNew.

Before calling OLE method, some kind of the ActiveX controls created with MFC should be initialized by calling IPersistXXX::InitNew.

If and only if you received the exception “HRESULT error code: 0x8000ffff catastrophic failure”, try this method before invoking any ole_method.

obj = WIN32OLE.new("ProgID_or_GUID_of_ActiveX_Control")
obj.ole_activex_initialize
obj.method(...)

WIN32OLE#ole_query_interface

Returns WIN32OLE object for a specific dispatch or dual interface specified by iid.

ie = WIN32OLE.new('InternetExplorer.Application')
ie_web_app = ie.ole_query_interface('{0002DF05-0000-0000-C000-000000000046}') # => WIN32OLE object for dispinterface IWebBrowserApp

Thread::abort_on_exception

Returns the status of the global “abort on exception” condition.

The default is false.

When set to true, if any thread is aborted by an exception, the raised exception will be re-raised in the main thread.

Can also be specified by the global $DEBUG flag or command line option -d.

Thread::abort_on_exception=

When set to true, if any thread is aborted by an exception, the raised exception will be re-raised in the main thread. Returns the new state.

Thread.abort_on_exception = true
t1 = Thread.new do
  puts  "In new thread"
  raise "Exception from thread"
end
sleep(1)
puts "not reached"

This will produce:

In new thread
prog.rb:4: Exception from thread (RuntimeError)
 from prog.rb:2:in `initialize'
 from prog.rb:2:in `new'
 from prog.rb:2

Thread::report_on_exception

Returns the status of the global “report on exception” condition.

The default is true since Ruby 2.5.

All threads created when this flag is true will report a message on $stderr if an exception kills the thread.

Thread.new { 1.times { raise } }

will produce this output on $stderr:

#<Thread:...> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
        2: from -e:1:in `block in <main>'
        1: from -e:1:in `times'

This is done to catch errors in threads early. In some cases, you might not want this output. There are multiple ways to avoid the extra output:

If the exception is not intended, the best is to fix the cause of the exception so it does not happen anymore.
If the exception is intended, it might be better to rescue it closer to where it is raised rather then let it kill the Thread.
If it is guaranteed the Thread will be joined with Thread#join or Thread#value, then it is safe to disable this report with Thread.current.report_on_exception = false when starting the Thread. However, this might handle the exception much later, or not at all if the Thread is never joined due to the parent thread being blocked, etc.

Thread::report_on_exception=

Returns the new state. When set to true, all threads created afterwards will inherit the condition and report a message on $stderr if an exception kills a thread:

Thread.report_on_exception = true
t1 = Thread.new do
  puts  "In new thread"
  raise "Exception from thread"
end
sleep(1)
puts "In the main thread"

This will produce:

In new thread
#<Thread:...prog.rb:2> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
prog.rb:4:in `block in <main>': Exception from thread (RuntimeError)
In the main thread

proc takes up to six parameters:

an event name string
a filename string
a line number
a method name symbol, or nil
a binding, or nil
the class, module, or nil

proc is invoked whenever an event occurs.

Events are:

"c-call": call a C-language routine
"c-return": return from a C-language routine
"call": call a Ruby method
"class": start a class or module definition
"end": finish a class or module definition
"line": execute code on a new line
"raise": raise an exception
"return": return from a Ruby method

Tracing is disabled within the context of proc.

class Test
  def test
    a = 1
    b = 2
  end
end

set_trace_func proc { |event, file, line, id, binding, class_or_module|
  printf "%8s %s:%-2d %16p %14p\n", event, file, line, id, class_or_module
}
t = Test.new
t.test

Produces:

c-return prog.rb:8   :set_trace_func         Kernel
    line prog.rb:11              nil            nil
  c-call prog.rb:11             :new          Class
  c-call prog.rb:11      :initialize    BasicObject
c-return prog.rb:11      :initialize    BasicObject
c-return prog.rb:11             :new          Class
    line prog.rb:12              nil            nil
    call prog.rb:2             :test           Test
    line prog.rb:3             :test           Test
    line prog.rb:4             :test           Test
  return prog.rb:5             :test           Test

ObjectSpace::trace_object_allocations

Starts tracing object allocations from the ObjectSpace extension module.

For example:

require 'objspace'

class C
  include ObjectSpace

  def foo
    trace_object_allocations do
      obj = Object.new
      p "#{allocation_sourcefile(obj)}:#{allocation_sourceline(obj)}"
    end
  end
end

C.new.foo #=> "objtrace.rb:8"

This example has included the ObjectSpace module to make it easier to read, but you can also use the ::trace_object_allocations notation (recommended).

Note that this feature introduces a huge performance decrease and huge memory consumption.

Gem::source_date_epoch

Returns the value of Gem.source_date_epoch_string, as a Time object.

This is used throughout RubyGems for enabling reproducible builds.

Gem::default_specifications_dir

Path to specification files of default gems.