Ruby Syntactic Sugar

Dustin Tang — Thu, 06 Jul 2006 03:01:00 GMT

有人说写Ruby就像写诗一样,咱就一土人, 没那么高境界. 我觉得写Ruby就像小时候吃糖, Ruby中就有各色各样的这种"语法糖果":
1. Hello World程序
Ruby : puts "Hello World!"
java : public class HelloWorld {
   public static void main(String[] args) {
    System.out.println("Hello World!");
   }
  }
2. Every Thing is object
Ruby : -1979.abs
java : -1979.abs (Error! Sorry, -1979 is primary type, it should be Math.abs(-1979))
3. String
"abcd\nefg" ==> abcd换行efg
'abcd\nefg' ==> abcd\nefg
a=123, "abcd#{a}efg" ==> abcd123efg 'abcd#{a}efg' ==> abcd#{a}efg
4. Control Structure
while line=gets
  puts line
end
puts line if line
5. Name convention
Local Variable : local_variable
Globle Variable : $globle_variable
instance : @instance
Class instance : @@class_instance
Constant and Class Name : ClassName
6. Hash
hash_map = {
  1 =>"1",
  2 =>"2"
}
hash_map[1] ==> "1"
7. Regular Expression
while line=gets
  puts line if line=~/Hello/
end
8. Attribute
A.
  def att=(att)
   @att=att
  end
  def att
   @att
  end
  class_object.att = 1;
B.
  attr_reader :att
  attr_writer :att
  class_object.att = 1;
9. asignment
a1, a2 = a2, a1
10. numbers
num = 81
6.times do
  puts "#{num.class}: #{num}"
  num *= num
end
Result :
Fixnum: 81
Fixnum: 6561
Fixnum: 43046721
Bignum: 1853020188851841
Bignum: 3433683820292512484657849089281
Bignum: 11790184577738583171520872861412518665678211592275841109096961
You can get number as big as you can, it depends your memory.
OK, I think for us, these are pretty much like opening acts, y'know? I mean it's like the stand-up comedian you have to sit through before Pink Floyd comes out.
下面出场的是Ruby中最大的糖果:
Blocks
Blocks在java世界中最密集的地区可能就是Spring Framework了.而在Ruby世界中,Block随处可见.
Block两种形式 :
单行 {内容在这里}
多行 do
  内容在这里
  还有这里
  end
1.upto(6) {puts "Hello, World!"} 打印六次Hello World
还可以带参数
1.upto(6) {|num| puts num} 打印1到6
原理(假代码)
class Number
  def upto(up)
   ini = @num
   while ini <= up
    yield(ini)
    ini+=1
   end
  end
end
解释器将 {|num| puts num}作为Call对象传入, yield就是调用此Call对象的方法.

Dustin Tang 2006-07-06 11:01 发表评论

Best of Ruby Quiz

Dustin Tang — Wed, 05 Jul 2006 06:50:00 GMT

一本好玩的书，里面有一些有趣的题目，　每天一题，　不亦乐乎
第一题　ＬＣＤ　Ｎｕｍｂｅｒｓ(电梯里面的数字见过吧, 把用户输入的数字转换为LCD的数字, 长7个字, 高7个字)

我的代码(初学者,大家就原谅则个)

class LCDNumber
  @@number_code = {
    "0" => 0b1110111,
    "1" => 0b0100100,
    "2" => 0b1011101,
    "3" => 0b1101101,
    "4" => 0b0101110,
    "5" => 0b1101011,
    "6" => 0b1111011,
    "7" => 0b0100101,
    "8" => 0b1111111,
    "9" => 0b1101111
  }
  def initialize(num)
    @num = num
  end
  def getZone(zone)
    if ((@@number_code[@num] & (1 << zone)) != 0)
      st = zone % 3 == 0 ? " -- " : (zone % 3 == 1 ? "| " : " |")
    else
      st = zone % 3 == 0 ? "    " : "  "
    end
    return st
  end
  attr_reader :num
end
def get(zone, array)
  s = ""
  for lcd_number in array
    s += (zone % 3 == 0 ? lcd_number.getZone(zone) : (zone % 3 == 1 ? lcd_number.getZone(zone) + lcd_number.getZone(zone+1) :  lcd_number.getZone(zone-1) + lcd_number.getZone(zone)))
  end
  return s
end
require "stringio"
while line=gets
  a = Array.new
  si = StringIO.new(line);
  while c=si.read(1)
    a.push(LCDNumber.new(c)) if (c >= '0' && c <= '9')
  end
  0.upto(6) {|line| puts get(line, a)}
end

Dustin Tang 2006-07-05 14:50 发表评论

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Ruby Syntactic Sugar

Best of Ruby Quiz