= 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

=== Compatibility issues

* language core

    * New syntax and semantics
          o Block arguments are always local
          o Block arguments
          o New semantics for block arguments
          o Block local variables
          o Method used for splat arguments: #to_splat instead of
            #to_ary
          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 uses.

* builtin classes and objects

    * Kernel and Object
          o Kernel#require
          o Kernel#methods used to return an array of strings but now
            it returns an array of symbols.
    * Class and Module
          o Class variables behavior
          o Module#attr is an alias of attr_reader
          o Module#instance_methods, #private_instance_methods,
            #public_instance_methods
          o Extra subclassing check when binding UnboundMethods
          o Module#instance_methods used to return an array of strings
            but now it returns an array of symbols.
    * Exceptions
          o Equality of exceptions
          o SystemStackError
          o SecurityError
          o Removed Exception#to_str [Ruby2]

    * 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.
    * Enumerable and Enumerator
          o Enumerable::Enumerator, compatibility alias of Enumerator,
            is removed.
          o Enumerable#map,collect_all 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.
    * 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 Dir.[], Dir.glob
          o Dir.exist?
    * String and Regexp
          o No longer an Enumerable
          o ?c semantics
          o "One-char-wide" semantics for String#[] and String#[]=
          o Character-wise semantics in many methods in stead of
            byte-wise.
          o Encoding-awareness
          o Regexp matches only with strings which is encoded in a
            compatible character encoding to the regexp's.
    * 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.
    * Numeric
          o Numeric#div always rounds as Integer#div has done.
          o Numeric#fdiv: ditto.
    * Integer
          o Integer(nil) raises TypeError
    * IO operations
          o IO#getc
          o Non-blocking IO
          o Kernel#open takes "t" for newline conversion
          o Kernel#open takes encoding specified
          o IO#initialize now accepts an IO argument
          o IO automatically converts byte sequence from a character
            encodings into another if specified.
          o StringIO#readpartial
          o IO.try_convert
          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#internal_encoding, IO#external_encoding,
            IO#set_encoding
          o IO.pipe takes encoding option
    * Struct
          o Struct#inspect
    * Symbols: restriction on literal symbols
    * $SAFE and bound methods
          o New trusted/untrusted model in addition to
            tainted/untainted model.
    * Time
          o New format in Time#to_s
          o Timezone information preserved on Marshal.dump/load
    * Deprecation
          o VERSION and friends
          o Kernel.to_a
          o Kernel#getc
          o Kernel#callcc and Continuation now become 'continuation'
            bundled library.
          o Object#type
          o Hash#index
          o ENV.index
          o Precision is removed.  Don't cry, it will be redesigned
            and come back in future version.
          o Symbol#to_int
          o Numeric#rdiv
          o Removed Array and Hash #indices, #indexes
          o $KCODE is no longer effective.  Use Encoding related
            features of each class.
          o mailread library
          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. realy?
          o ftools library: use fileutils.
          o generator library: use Enumerator.
          o importenv 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.
          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.

* bundled libraries

    * Readline
          o If Readline uses libedit, Readline::HISTORY[0] returns the
            first of the history.
    * Pathname
          o No longer has #to_str and #=~
    * Continuation
          o as above

=== 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
          o New syntax for lambdas
          o .() and calling Procs without #call/#[]
          o Mandatory arguments after optional arguments allowed
          o Multiple splats allowed
          o Arguments to #[]
          o printf-style formatted strings (%)
          o Newlines allowed before ternary colon
          o Encoding.default_external and default_internal

=== Library updates

    * Kernel and Object
          o BasicObject
          o Object#=~
          o Kernel#instance_variable_defined?
          o Kernel#define_singleton_method
          o Kernel#singleton_methods, Kernel#methods
    * Class and Module
          o Module#const_defined?, #const_get and #method_defined?
          o Module#class_variable_defined?
          o #class_variable_{set,get}
          o Class of singleton classes
    * Binding#eval
    * Blocks and Procs
          o Arity of blocks without arguments
          o proc is now a synonym of Proc.new
    * Blocks and Procs
          o Proc#yield
          o Passing blocks to #[]
          o Proc#lambda?
    * Enumerable and Enumerator
          o Enumerable#each_with_object
          o Enumerator#with_object
          o Enumerator.new { ... }
    * Errno::EXXX
          o All of those are always defined.  Errno::EXX will be
            defined as an alias to Errno::ENOERROR if your platform
            does not have one.
    * Regexp#match, String#match
          o Regexp#match, String#match
    * Encoding
    * Encoding::Converter
          o supports conversion between many encodings
    * Fiber: coroutines/micro-threads
    * 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
    * Numeric
          o Numeric#upto, #downto, #times, #step
          o Numeric#scalar?, Complex#scalar?
    * 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
    * Regexp
          o Regexp#=== matches symbols
          o Regexp.try_convert
    * String
          o String#clear
          o String#ord
          o String#getbyte, String#setbyte
          o String#encoding
          o String#force_encoding
          o String#unpack with a block
          o String#hash
          o String.try_convert
          o String.encoding, String#force_encoding, String#encode
    * Symbol
          o Zero-length symbols allowed
          o Symbol#=== matches strings
          o Symbol#intern
          o Symbol#encoding
          o Symbol methods similar to those in String
    * Math
          o Math#log and Math#log2
          o Math#cbrt, Math#lgamma
    * Rational / Complex
          o They are core library now
    * File and Dir operations
          o New methods
    * Process
          o Process.daemon
    * Readline
          o Readline.vi_editing_mode?
          o Readline.emacs_editing_mode?
          o Readline::HISTORY.clear
    * Misc. new methods
          o RUBY_ENGINE to distinguish between Ruby processor implementation
          o public_send
          o GC.count
          o ObjectSpace.count_objects
          o Method#hash, Proc#hash
          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 cleaner and easier to
            read than the old test/unit.
          o You can introduce the old test/unit as a gem through
            RubyGems if you want.
    * CMath
          o Complex number version of Math
    * Prime
          o Extracted from Mathn and improved. You can easily iterate
            prime numbers.
          o Prime.new is obsolete. Use its class methods.
    * ripper
          o Ruby script parser

* 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, human68k, MacOS 9 or earlier,
            VMS nor Windows CE.