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

=== 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
          o defined? and local variables

* builtin classes and objects

    * Kernel and Object
          o Kernel#require
    * 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
    * 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#map,collect called without a block returns
            an enumerator.
    * File and Dir operations
          o #to_path in File.path, File.chmod, File.lchmod, File.chown, File.lchown, File.utime, File.unlink... [Ruby2]
          o Dir.[], Dir.glob
          o Dir.exist?
    * String
          o No longer an Enumerable
          o ?c semantics
          o "One-char-wide" semantics for String#[] and String#[]= [Ruby2]
          o Encoding-awareness
    * 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 Most of the changes in Hash apply to hash like interfaces such as
            ENV and *DBM.
    * 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 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
    * Time
          o New format in Time#to_s
          o Timezone information preserved on Marshal.dump/load
    * Struct
          o Struct#inspect
    * Symbols: restriction on literal symbols
    * $SAFE and bound methods
    * Deprecation
          o VERSION and friends
          o Kernel.to_a
          o Kernel#getc
          o Object#type
          o Hash#index
          o ENV.index
          o Symbol#to_int
          o Removed Array and Hash #indices, #indexes
	  o libraries: base64, mailread, getopts, parsearg, soap, wsdl

* bundled libraries

    * Readline
          o If Readline uses libedit, Readline::HISTORY[0] returns the first of the history.

=== Language core changes

    * New syntax and semantics
          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

=== 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 [experimental]
          o Enumerator#with_object
          o Enumerator.new { ... }
    * Regexp#match, String#match
          o Regexp#match, String#match
    * Encoding
    * Encoding::Converter
    * 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
    * 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#real?, Complex#real?
          o Numeric#div
          o Numeric#fdiv
    * 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
    * 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 public_send
          o GC.count
          o ObjectSpace.count_objects
          o Method#hash, Proc#hash
          o __callee__

=== Implementation changes

    * Memory Diet
      * Object Compaction - Object, Array, String, Hash, Struct, Class, Module
      * st_table compaction (inlining small tables)
    * YARV