NEWS-1.9.1

= NEWS

This document is a list of user visible feature changes made between
releases except for bug fixes.

Note that each entry is kept so brief that no reason behind or
reference information is supplied with.  For a full list of changes
with all sufficient information, see the ChangeLog file.

== Changes since the 1.8.7 release
See doc/NEWS-1.8.7 for changes between 1.8.6 and 1.8.7.

=== Compatibility issues

* language core

    * New syntax and semantics
          o Block arguments are always local
          o New semantics for block arguments
          o defined? and local variables
          o Parser expects that your source code has only valid byte
            sequence in some character encoding.  Use magic comments
            to tell the parser which encoding you use.
          o New semantics for constant definition in instance_eval
            or in module_eval.

    * Deprecated syntax
          o colon (:) instead of "then" in if/unless or case expression.
          o retry in a loop or an iterator.

* builtin classes and objects

    * Kernel and Object
          o Kernel#methods and #singleton_methods used to return an 
            array of strings but now they return an array of symbols.
    * Class and Module
          o Module#attr works as Module#attr_reader by default.
	    Optional boolean argument is obsolete.
          o Module#instance_methods, #private_instance_methods and
            #public_instance_methods used to return an array of 
            strings but now they return an array of symbols.
          o Extra subclassing check when binding UnboundMethods
            
    * Exceptions
          o Exceptions are equal to each other if they belong to 
            the same class and have the same message and backtrace.
          o SystemStackError used to be a subclass of StandardError
            but not it is a direct subclass of Exception.
          o SecurityError: ditto
          o Removed Exception#to_str [Ruby2]

    * Enumerable and Enumerator
          o Enumerable::Enumerator, compatibility alias of Enumerator,
            is removed.
          o Enumerable#{map,collect} called without a block returns
            an enumerator.
          o Even more builtin and bundled libraries have been made to
            return an enumerator when called without a block.
    * Array
          o Array#nitems was removed (use count {|i| !i.nil?})
          o Array#choice was removed (use sample)
          o Array#[m,n] = nil places nil in the array.
    * Hash
          o Hash#to_s is equivalent to Hash#inspect
          o Semantics for Hash#each and Hash#each_pair
          o Hash#select returns a hash
          o Hash#key is the new name for #index which has been
            deprecated.
          o Hash preserves order.  It enumerates its elements in the
            order in which the keys are inserted.
          o Most of the changes in Hash apply to hash like interfaces
            such as ENV and *DBM.
    * IO operations
          o Many methods used to act byte-wise but now some of those act 
            character-wise. You can use alternate byte-wise methods.
          o IO#getc
          o Non-blocking IO
          o Kernel#open takes "t" for newline conversion
          o Kernel#open takes encoding specified
          o IO automatically converts byte sequence from a character
            encodings into another if specified.
          o StringIO#readpartial
          o IO.try_convert
          o IO.binread
          o IO.copy_stream
          o IO#binmode?
          o IO#close_on_exec= and IO#close_on_exec?
          o Limit input in IO#gets, IO#readline, IO#readlines,
            IO#each_line, IO#lines, IO.foreach, IO.readlines,
            StringIO#gets, StringIO#readline, StringIO#each,
            StringIO#readlines
          o IO#ungetc, StringIO#ungetc
          o IO#ungetbyte, StringIO#ungetbyte
          o IO#internal_encoding, IO#external_encoding,
            IO#set_encoding
          o IO.pipe takes encoding option
          o Directive %u behaves like %d for negative values in 
            printf-style formatting.
    * File and Dir operations
          o #to_path is called as necessary in File.path, File.chmod,
            File.lchmod, File.chown, File.lchown, File.utime,
            File.unlink, etc..
          o File.world_readable?
          o File.world_writable?
          o Dir.[], Dir.glob
          o Dir.exist?
          o Dir.exists?
    * File::Stat
          o File::Stat#world_readable?
          o File::Stat#world_writable?
    * String
          o No longer an Enumerable: use each_line/lines for line
            oriented operation
          o Encoding-awareness
              o Character-wise semantics in many methods instead of
                byte-wise.
                  o String#[]: Indexing a String with an integer returns a
                    single character String instead of an integer.
                  o String#[]=: No longer takes an integer as right
                    side value.  Note that "str[i] = ?c" because of
                    the following change.
                  o ?c is evaluated to a single character string
                    instead of an integer.
    * Regexp
          o Encoding-awareness
          o Regexp matches only with strings which is encoded in a
            compatible character encoding to the regexp's.
          o Regexp#kcode is removed. use Regexp#encoding.
    * Symbols: restriction on literal symbols
    * Numeric
          o Numeric#div always rounds as Integer#div has done.
          o Numeric#fdiv: ditto.
    * Integer
          o Integer(nil) raises TypeError
    * Fixnum
          o Fixnum#id2name removed
          o Fixnum#to_sym removed
    * Struct
          o Struct#inspect
    * Time
          o New format in Time#to_s
          o Timezone information preserved on Marshal.dump/load
    * $SAFE and bound methods
          o New trusted/untrusted model in addition to
            tainted/untainted model.

    * Deprecation
          o $= (global flag for case-sensitiveness on string matching)
          o Kernel#to_a
          o Kernel#getc, #gsub, #sub
          o Kernel#callcc and Continuation now become 'continuation'
            bundled library.
          o Object#type
          o Removed Array and Hash #indices, #indexes
          o Hash#index
          o ENV.index
          o Process::Status#to_int
          o Numeric#rdiv
          o Precision is removed.  Don't cry, it will be redesigned
            and come back in future version.
          o Symbol#to_int and Symbol#to_i
          o $KCODE is no longer effective.  Use Encoding related
            features of each class.
          o VERSION and friends

* bundled libraries

    * Pathname
          o No longer has #to_str nor #=~.
    * time and date
          o Time.parse and Date.parse interprets slashed numerical dates 
	    as "dd/mm/yyyy".
    * Readline
          o If Readline uses libedit, Readline::HISTORY[0] returns the
            first of the history.
    * Continuation
          o as above

    * Deprecation
          o Complex#image: use Complex#imag
          o All SSL-related class methods in Net::SMTP
          o Prime#cache, Prime#primes, Prime#primes_so_far
          o mailread library: use tmail gem.
          o cgi-lib library: use cgi.
          o date2 library: use date.
          o eregex library
          o finalize library: use ObjectSpace.define_finalizer if you
            really need a finalizer. really?
          o ftools library: use fileutils.
          o generator library: use Enumerator.
          o importenv library and Env library
          o jcode library: use multilingualization support of String
          o parsedate library
          o ping library
          o readbytes library
          o getopts library and parsearg library: use optparse or
            getoptlong.
          o soap, wsdl and xsd libraries: use soap4r gem.
          o Win32API library: use dl.
          o dl library: Reimplemented and API changed. use the new
	    version of dl or ffi gem.
          o rubyunit library and runit library: use minitest or
            test/unit. Or use anything you love through RubyGems.
          o test/unit is reimplemented on top of minitest.  This is
            not fully compatible with the original.

=== Language core changes

    * New syntax and semantics
          o Magic comments to declare in which encoding your source
            code is written
          o New literal hash syntax and new syntax for hash style 
	    arguments 
          o New syntax for lambdas
          o .() and calling Procs without #call/#[]
          o Block in block arguments
          o Block local variables
          o Mandatory arguments after optional arguments allowed
          o Multiple splats allowed
          o #[] can take splatted arguments, hash style arguments 
            and a block.
          o New directives in printf-style formatted strings (%).
          o Newlines allowed before ternary colon operator (:) and
            method call dot operator (.)
          o Negative operators such as !, != and !~ are now
            overloadable
          o Encoding.default_external and default_internal
          o __ENCODING__: New pseudo variable to hold the current
            script's encoding

=== Library updates

* builtin classes and objects
    * Kernel and Object
          o BasicObject
          o Object#=~ returns nil instead of false by default.
          o Kernel#define_singleton_method
	  o Kernel#load can load a library from the highest versions
	    of gems by default.
    * Class and Module
          o Module#const_defined?, #const_get and #method_defined?
            take an optional parameter.
          o #class_variable_{set,get} are public.
          o Class of singleton classes

    * Errno::EXXX
          o All of those are always defined.  Errno::EXXX will be
            defined as an alias to Errno::NOERROR if your platform
            does not have one.

    * Binding#eval
    * Blocks and Procs
          o Arity of blocks without arguments
          o proc is now a synonym of Proc.new
          o Proc#yield
          o Passing blocks to #[]
          o Proc#lambda?
          o Proc#curry
    * Fiber: coroutines/micro-threads
    * Thread
          o Thread.critical and Thread.critical= removed
          o Thread#exit!, Thread#kill! and Thread#terminate! removed.

    * Enumerable and Enumerator
          o Enumerator#enum_cons and Enumerator#enum_slice are
            removed.  Use #each_cons and #each_slice without a block.            
          o Enumerable#each_with_index can take optional arguments
            and passes them to #each.
          o Enumerable#each_with_object
          o Enumerator#with_object
          o Enumerator.new { ... }
    * Array
          o Array#delete returns a deleted element rather than a given
            object
          o Array#to_s is equivalent to Array#inspect
          o Array.try_convert
          o Array#pack('m0') complies with RFC 4648.
    * Hash
          o preserving item insertion order
          o Hash#default_proc=
          o Hash#_compare_by_identity and Hash#compare_by_identity?
          o Hash.try_convert
          o Hash#assoc
          o Hash#rassoc
          o Hash#flatten
    * Range
          o Range#cover?
          o Range#include? iterates over elements and compares the
            given value with each element unless the range is numeric.
            Use Range#cover? for the old behavior, i.e. comparison
            with boundary values.
          o Range#min, Range#max

    * File and Dir operations
          o New methods
    * Process
          o Process.spawn
          o Process.daemon
    * String
          o String#clear
          o String#ord
          o String#getbyte, String#setbyte
          o String#chars and String#each_char act as character-wise.
          o String#codepoints, String#each_codepoint
          o String#unpack with a block
          o String#hash
          o String.try_convert
          o String#encoding
	  o String#force_encoding, String#encode and String#encode!
          o String#ascii_only?
          o String#valid_encoding?
	  o String#match
    * Symbol
          o Zero-length symbols allowed
          o Symbol#intern
          o Symbol#encoding
          o Symbol methods similar to those in String
    * Regexp
          o Regexp#=== matches symbols
          o Regexp.try_convert
          o Regexp#match
          o Regexp#fixed_encoding?
          o Regexp#encoding
          o Regexp#named_captures
          o Regexp#names
    * MatchData
          o MatchData#names
          o MatchData#regexp
    * Encoding
    * Encoding::Converter
          o supports conversion between many encodings
    * Numeric
          o Numeric#upto, #downto, #times, #step
          o Numeric#real?, Complex#real?
          o Numeric#magnitude
    * Rational / Complex
          o They are in the core library now
    * Math
          o Math#log takes an optional argument.
          o Math#log2
          o Math#cbrt, Math#lgamma, Math#gamma
    * Time
          o Time.times removed.  Use Process.times.
          o Time#sunday?
          o Time#monday?
          o Time#tuesday?
          o Time#wednesday?
          o Time#thursday?
          o Time#friday?
          o Time#saturday?
          o Time#tv_nsec and Time#nsec
    * Misc. new methods
          o RUBY_ENGINE to distinguish between Ruby processor implementation
          o public_method
          o public_send
          o GC.count
          o ObjectSpace.count_objects
          o Method#hash, Proc#hash
          o Method#source_location, UnboundMethod#source_location and
	    Proc#source_location
          o __callee__
          o Elements in $LOAD_PATH and $LOADED_FEATURES are expanded

* bundled libraries
    * RubyGems
          o Package management system for Ruby.
          o Integrated with Ruby's library loader.
    * Rake
          o Ruby make. A simple ruby build program with capabilities
            similar to make.
    * minitest
          o Our new testing library which is faster, cleaner and easier
	    to read than the old test/unit.
          o You can introduce the old test/unit as testunit gem through
            RubyGems if you want.
    * CMath
          o Complex number version of Math
    * Prime
          o Extracted from Mathn and improved. You can easily enumerate
            prime numbers.
          o Prime.new is obsolete. Use its class methods.
    * ripper
          o Ruby script parser
    * Readline
          o Readline.vi_editing_mode?
          o Readline.emacs_editing_mode?
          o Readline::HISTORY.clear
    * Tk
          o TkXXX widget classes are removed and redefined as aliases of 
            Tk::XXX classes.
    * RDoc
          o Updated to version 2.2.2.  See:
            http://rubyforge.org/frs/shownotes.php?group_id=627&release_id=26434
    * json
          o JSON (JavaScript Object Notation) encoder/decoder

* commandline options
    * -E, --encoding
    * -U
    * --enable-gems, --disable-gems
    * --enable-rubyopt, --disable-rubyopt
    * long options are allowed in RUBYOPT environment variable.

=== Implementation changes

* Memory Diet
    * Object Compaction - Object, Array, String, Hash, Struct, Class,
      Module
    * st_table compaction (inlining small tables)
* YARV
    * Ruby codes are compiled into opcodes before executed.
    * Native thread

* Platform supports
    * Support levels
          (0) Supported
          (1) Best effort
          (2) Perhaps
          (3) Not supported
    * Dropped
          o No longer supports djgpp, bcc32, human68k, MacOS 9 or earlier,
            VMS nor Windows CE.