Other Builtin Classes

There are many other classes builtin into the Ruby interpreter, some of these are:

• Dir

  to manage directory and files, with functions as: chdir, pwd, exists?, mkdir, new, delete.

  There are also some iterators on files.

  Dir.pwd is the current directory.

• Exception

  to manage exceptions with methods: message , status, success? (true is status zero or nil)

  to_s : a string representation of the message

• File

  represents files, with all the unix functions for files and more, as: atime, ctime, dirname, executable?, directory?, file? ,exists?, readable? ,zero?, truncate, delete, new, rename, ftype, lstat ,link, symlink, path, size, stat

• IO

  for input/output and functions as: new, pipe, open, read, write, sync, eof?, and many iterators on the file content.

• Mutex

  a semaphore for synchronization of accesses to resources

• Random

  random numbers

• Struct

  A mini-class to contain strings which can be accessed by symbols:

  Customer = Struct.new(:name, :surname) # => makes the Customer object
  
  c1=Customer.new("giovanni", "bianco")   # makes  instances
  c2=Customer.new("giovanna","rossi")
  
  c1.name    => "giovanni"         # using builtin accessors
  c1["name"] => "giovanni"
  
  c1.members=> [:name, :surname]   # using symbols as  accessors
  
  c1.to_a    => ["giovanni", "bianco"]
  
  c1.to_h    :  make an hash ( only for Ruby 2 )
  

• Thread

  to manage threads , with function as fork, kill , new, stop.

• Time

  class for time and date:

  t = Time.at(0)                         => 1970-01-01 01:00:00 +0100
  
  t1= Time.gm(2000,"jan",1,20,15,1)      => 2000-01-01 20:15:01 UTC
  
  t2= Time.local(2000,"jan",1,20,15,1)   => 2000-01-01 20:15:01 -0600
  
  t3= Time.new(2010, 12, 25, 8, 0, 0, "-06:00") # => 2010-12-25 08:00:00 -0600
  
  tn=Time.now         => 2014-08-27 16:04:34 +0200
  
  tn.getgm            => 2014-08-27 14:06:40 UTC    # convert from local to UTC
  
  Time.now.asctime    => "Wed Aug 27 16:05:51 2014" # as an ASCII string
  
  tn.strftime(special string )     # formatted as in the printf function of C
  tn.strftime("today is %d/%m/%Y %H:%S")  => "today is 27/08/2014 16:40"
  
  tn.to_a     => [40, 6, 16, 27, 8, 2014, 3, 239, true, "CEST"] # as an array
  
  to_f ; to_i => giulian seconds from  1870
  
  localtime ; gmtime ; =>  convert times  in place
  

  Parts of the data can be obtained by:

  t = Time.at(0)
  
  t.min  ;  t.sec ; t.hour;
  t.hour ;  t.day ; t.mon; t.year;  t.zone ;
  t.wday ;  t.mday;
  
  t.sec ; t.usec ; t. nsec  => in julian seconds, microseconds, nanoseconds