Results for: "String#[]"

Deletes the named files, returning the number of names passed as arguments. Raises an exception on any error. Since the underlying implementation relies on the unlink(2) system call, the type of exception raised depends on its error type (see linux.die.net/man/2/unlink) and has the form of e.g. Errno::ENOENT.

See also Dir::rmdir.

Truncates the file file_name to be at most integer bytes long. Not available on all platforms.

f = File.new("out", "w")
f.write("1234567890")     #=> 10
f.close                   #=> nil
File.truncate("out", 5)   #=> 0
File.size("out")          #=> 5

Returns a new string formed by joining the strings using "/".

File.join("usr", "mail", "gumby")   #=> "usr/mail/gumby"

Same as IO#stat, but does not follow the last symbolic link. Instead, reports on the link itself.

File.symlink("testfile", "link2test")   #=> 0
File.stat("testfile").size              #=> 66
f = File.new("link2test")
f.lstat.size                            #=> 8
f.stat.size                             #=> 66

Truncates file to at most integer bytes. The file must be opened for writing. Not available on all platforms.

f = File.new("out", "w")
f.syswrite("1234567890")   #=> 10
f.truncate(5)              #=> 0
f.close()                  #=> nil
File.size("out")           #=> 5

Return true if the named file exists.

file_name can be an IO object.

“file exists” means that stat() or fstat() system call is successful.

Returns true if the named file is writable by the effective user and group id of this process. See eaccess(3).

Note that some OS-level security features may cause this to return true even though the file is not writable by the effective user/group.

Returns true if the named file is a symbolic link.

Returns true if the named file has the sticky bit set.

file_name can be an IO object.

Returns a string which represents the encoding for programmers.

Encoding::UTF_8.inspect       #=> "#<Encoding:UTF-8>"
Encoding::ISO_2022_JP.inspect #=> "#<Encoding:ISO-2022-JP (dummy)>"

Returns the list of loaded encodings.

Encoding.list
#=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>,
      #<Encoding:ISO-2022-JP (dummy)>]

Encoding.find("US-ASCII")
#=> #<Encoding:US-ASCII>

Encoding.list
#=> [#<Encoding:ASCII-8BIT>, #<Encoding:UTF-8>,
      #<Encoding:US-ASCII>, #<Encoding:ISO-2022-JP (dummy)>]

Search the encoding with specified name. name should be a string.

Encoding.find("US-ASCII")  #=> #<Encoding:US-ASCII>

Names which this method accept are encoding names and aliases including following special aliases

“external”

default external encoding

“internal”

default internal encoding

“locale”

locale encoding

“filesystem”

filesystem encoding

An ArgumentError is raised when no encoding with name. Only Encoding.find("internal") however returns nil when no encoding named “internal”, in other words, when Ruby has no default internal encoding.

Rewinds the enumeration sequence to the beginning.

If the enclosed object responds to a “rewind” method, it is called.

Creates a printable version of e.

Return this exception’s class name and message.

Returns any backtrace associated with the exception. The backtrace is an array of strings, each containing either “filename:lineNo: in ‘method”’ or “filename:lineNo.”

def a
  raise "boom"
end

def b
  a()
end

begin
  b()
rescue => detail
  print detail.backtrace.join("\n")
end

produces:

prog.rb:2:in `a'
prog.rb:6:in `b'
prog.rb:10

In the case no backtrace has been set, nil is returned

ex = StandardError.new
ex.backtrace
#=> nil

Return the status value associated with this system exit.

Invokes Module.append_features on each parameter in reverse order.

Refine mod in the receiver.

Returns a module, where refined methods are defined.

In the first form, returns an array of the names of all constants accessible from the point of call. This list includes the names of all modules and classes defined in the global scope.

Module.constants.first(4)
   # => [:ARGF, :ARGV, :ArgumentError, :Array]

Module.constants.include?(:SEEK_SET)   # => false

class IO
  Module.constants.include?(:SEEK_SET) # => true
end

The second form calls the instance method constants.

Callback invoked whenever the receiver is included in another module or class. This should be used in preference to Module.append_features if your code wants to perform some action when a module is included in another.

module A
  def A.included(mod)
    puts "#{self} included in #{mod}"
  end
end
module Enumerable
  include A
end
 # => prints "A included in Enumerable"

Returns true if module is included or prepended in mod or one of mod’s ancestors.

module A
end
class B
  include A
end
class C < B
end
B.include?(A)   #=> true
C.include?(A)   #=> true
A.include?(A)   #=> false

Returns a list of modules included/prepended in mod (including mod itself).

module Mod
  include Math
  include Comparable
  prepend Enumerable
end

Mod.ancestors        #=> [Enumerable, Mod, Comparable, Math]
Math.ancestors       #=> [Math]
Enumerable.ancestors #=> [Enumerable]

The first form is equivalent to attr_reader. The second form is equivalent to attr_accessor(name) but deprecated. The last form is equivalent to attr_reader(name) but deprecated. Returns an array of defined method names as symbols.

Returns an array of the names of the constants accessible in mod. This includes the names of constants in any included modules (example at start of section), unless the inherit parameter is set to false.

The implementation makes no guarantees about the order in which the constants are yielded.

IO.constants.include?(:SYNC)        #=> true
IO.constants(false).include?(:SYNC) #=> false

Also see Module#const_defined?.