ruby1.8 1.9问题

1：正式的参数不能使实例变量

Ruby1.8

class Foo
  attr_accessor :bar
  def test
     [1,2,3].each {|@bar| }
     # @bar will be 3 here
  end
end

Ruby1.9

class Foo
  attr_accessor :bar
  def test
     [1,2,3].each {|bar| @bar=bar }
     # @bar will be 3 here
  end
end

2：覆盖外部局部变量

i =0 
[1,2,3].each { |i|  }
puts i
ruby1.8输出3  ruby1.9输出0

3: hash语法 ” , “ 问题

ruby 1.8 {"a","b"} => {"a"=> "b"}

ruby 1.9 {"a" =>＂ｂ＂}

４：字符

默认是 US-ASCIi 码 如果不是的话 用 coding :utf-8

5: String的 ‘to_a’方法未定义

1.8 : string.to_a

1.9 : string.lines.to_a

为了解决兼容性问题keyi :

if str.respond_to?(:lines) then
  lines = string.lines.to_a
else
  lines = string.to_a
end

6: 关键字 then , ; /n case if 可以使用： 代替

1.8:

case 'test'
when'test':print 'OK'
end

1.9:

case 'test'
when'test' then print 'OK'
end

7:no such file to load -base64:

require "base64": ruby 1.9 ships without base64. You should use Array#pack, unpack
require 'base64'
 enc = Base64.encode64('Send reinforcements')
 plain = Base64.decode64(enc)
In ruby1.9 you can write:
enc = ['Send reinforcements'].pack( 'm' )
plain = enc.unpack( 'm' )[0]

8:'结构体 RStirng没有成员‘ptr’ len

In ruby1.9 for the RString in C extensions was changed because of optimization, you should use the RSTRING_LEN, RSTRING_PTR macros instead of directly accessing the len, ptr members.
len = RSTRING(foo)->len
ptr = RSTRING(foo)->ptr
Should be changed to
len = RSTRING_LEN(foo);
ptr = RSTRING_PTR(foo);

9:成员改变从Strings转化到Symbols

Object.methods.include?("to_s")
The ruby1.9 version is:
Object.methods.include?(:to_s)
And the following works in ruby1.8 and 1.9:
object.respond_to?(:some_method)

10：TypeErro：不能分配nil；要用Hash#delete 代替

n ruby1.8 you can remove an environment variable by setting it to nil.
In ruby1.9 use the delete method instead:
ENV.delete('MY_ENV_VARIABLE')