Install Ruby（安装）

For windows you can download Ruby from http://rubyforge.org/frs/?group_id=167 

for Linux tryhttp://www.rpmfind.net.

Our first program（从此开始）

Enter the following into the file, "test.rb".

Output in Ruby

"puts" 写到屏幕上，并带有个换行，writes to the screen with a carriage return at the end. 
"print" 写到屏幕，但没有换行，does the same thing without the carriage return. 
"printf" 格式化输出到屏幕，formats variables like in C and Java 5.

Reading from the Console（接受控制台输入）

Use "gets"

Functions（函数）

1. Our first Ruby function最开始的函数

   “def”用于定义函数，以“end”结束函数定义。

   ?

   1 2 3 4

   def welcome(name)    puts "howdy #{name}"   # 必须包含在双引号内, #{ } 用来包含变量 end welcome("nana")           # traditional parens

   This Produces:

   howdy nana
   

2. Parentheses are optional（括号可省略）
   ?

   1 2 3

   def welcome(name)    puts "howdy #{name}"   # inside double quotes, #{ } will evaluate the variable end

   welcome "visitor" #look, ma, no parentheses

   This Produces:

   howdy visitor
   

   如果没有参数，用不用括号都一样

   ?

   1 2	"hello".upcase() => "HELLO" "hello".upcase => "HELLO"

3. How to return values from a function（函数返回值）

   可以使用return语句

   ?

   1 2 3 4 5

   def multiply(a,b)   product = a * b   return product end puts multiply(2,3)   =>6

   函数定义内部最后一个表达式，默认做为返回值返回。

   ?

   1 2 3 4

   def mult(a,b)   product = a * b end puts mult(2,3)

   所以上面的product变量可以去掉了

   ?

   1 2 3 4

   def mult(a,b)    a * b end puts mult(3,3)   =>9

4. Optional argument values（默认参数）

   Ruby lets you assign values to arguments which may, or may not be supplied as shown below:

   ?

   1 2 3 4 5 6 7

   def test(a=1,b=2,c=a+b)   puts "#{a},#{b},#{c}" end test        =>  1,2,3 test 5      =>  5,2,7 test 4, 6   =>  4,6,10 test 3, 4, 6   =>  3,4,6

5. Extra arguments额外的参数

   Extra arguments是前面加一个星号的，并且要放在所有参数的最后 

   ?

   1 2 3 4 5

   def test(a=1,b=2,*c)   puts "#{a},#{b}"   c.each{|x| print " #{x}, "}  # We will learn about "each" very soon.  I promise. end test 3, 6, 9, 12, 15, 18

   This produces:

   3,6
    9,  12,  15,  18,

6. Multiple return values（多个返回值）
   ?

   1 2 3 4 5 6 7

   def getCostAndMpg     cost = 30000  # some fancy db calls go here     mpg = 30     return cost,mpg end AltimaCost, AltimaMpg = getCostAndMpg puts "AltimaCost = #{AltimaCost}, AltimaMpg = #{AltimaMpg}"

   Produces:

   AltimaCost = 30000, AltimaMpg = 30

Open Classes（开放的类）

You can add methods to existing library classes.可以给已经存在的库中的类，增加新的方法。

给String类增加一个新的方法

Is this way cool? Yes. Is this very dangerous? Yes. Remember, Ruby is a chainsaw.

Variable naming（变量命名规则）

1. Global variables start with ‘$‘ 全局变量用$开头
2. Class variables start with ‘@@‘ 类变量用@@开头
3. Instance variables start with ‘@‘ 实例变量用@开头
4. Local variables, method names, and method parameters start with a lower case letter 本地变量，方法名，方法参数用小写字母开头
5. Class names, module names and constants start with an uppercase letter 类名，模块名，常量用大写字母开头
6. Variables names are composed of letters, numbers and underscores 变量名由小写字母、数字和下划线组成
7. Method names may end with "?", "!", or "=". Methods ending with a "?" imply a boolean operation (eg, "instance_of?"). Methods ending with "!" imply something dangerous, like strings being modified in place (eg, "upcase!") 方法名可以用？（表示执行一个布尔操作）、！（表示执行一些危险的操作，可能会修改传入的参数）、=结尾；

Interesting tidbits about Ruby有趣的花絮

1. ‘#‘ is the line comment character, all characters after this are ignored. Confusingly ‘#‘ can appear within quotes with a different meaning. #注释一行
2. No semi-colons are needed to end lines, but may be used to separate statements on the same line
3. A backslash (\) at the end of a line is used for continuation
4. Indenting is not significant, unlike python
5. Types of variables do not need to be declared
6. Lines between =begin and =end are ignored
7. Lines following "__END__" on its own line with no white space, are ignored
8. A tiny demonstration of these:
   
   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

   # sample program showing special characters like comments # I‘m a comment line a = 1  #notice no semicolon and no type declaration b = 2; c = 3 #notice two statements on one line name = "Abraham \ Lincoln"   # a line continued by trailing \ puts "#{name}" =begin I‘m ignored. So am I. =end puts "goodbye" __END__ 1 2 3 4 Abraham Lincoln goodbye

Variable Types

In Ruby, variables don‘t have a specific type associated with them.

All variables are objects, so we only play with pointers to those objects, and those pointers are type agnostic.

1. bat = "Louisville slugger"
   bat = 1.23

2. Quotes（引号）

   Like in Perl, single quotes and double quotes have different meanings.

   Double quotes means "please interpret special characters in this string". Things like backslash n (‘\n‘) are converted to their typical values. The #{name} construct is converted to its value.

   With single quotes, no special characters are interpreted.

   Examples:

   ?

   1 2 3 4

   name="Mike" puts "hi #{name}" =>hi Mike puts "hi\n #{name}" => hi (carriage return)Mike puts ‘hi\n #{name}‘ => hi\n #{name}    (no substitutions are made since using single quote)

   The braces are optional for global and instance variables

   ?

   1 2	$myname="Ishmael" puts "hi #$myname" =>hi Ishmael

3. Objects

   A great thing about Ruby is that numbers and strings are real objects.

   ?

   1	1.5.floor()   => "1"

   This lets us do some cool things. Instead of

   if( x > 7 && x < 12 ) { ... }

   We can write

   if x.between?(7,12) do ...

4. Big Numbers

   Ruby automatically increases the precision of variables

   ?

   1 2 3

   for i in 1..1000   puts "2 ** #{i} = #{2**i}" end

   Produces:

   2 ** 1 = 2
   2 ** 2 = 4
   2 ** 3 = 8
   2 ** 4 = 16
   2 ** 5 = 32
   2 ** 6 = 64
   2 ** 7 = 128
   2 ** 8 = 256
   2 ** 9 = 512
   2 ** 10 = 1024
   ...
   2 ** 1000 = 107150860718626732094842504906000181056140481170553360744375038837035105112493612249319837881569585812759467291755314682518714528569231404
   359845775746985748039345677748242309854210746050623711418779541821530464749835819412673987675591655439460770629145711964776865421676604298316526243868
   37205668069376

   Ruby will increase the precision of the number, or decrease it as needed:

   ?

   1 2 3 4 5 6

   x = 1000000 puts "#{x}  "+x.class.to_s    => 1000000  Fixnum x = x * x puts "#{x}  "+x.class.to_s    => 1000000000000  Bignum x = x / 1000000 puts "#{x}  "+x.class.to_s    => 1000000  Fixnum

Parallel Assignment（交换参数）

You can swap the values in variables without the use of a temp variable. Remember your first programming class: Swap the values in "i" and "j"? You had to use a "t" variable to store one of the values first. Not needed in Ruby.

Produces:

i = 0, j=1
i = 1, j=0

Collections

Arrays

1. An array of known objects can be created by enclosing them in square brackets.
   ?

   1 2	nums = [1, 2.0, "three"] puts nums[2]  => three

   Ruby arrays, like all right-thinking collections, are zero based.

2. You can use negative indexes to start from the end of the array

   ?

   1 2	nums = [1, 2.0, "three", "four"] puts nums[-1]   => four

   Using "-1" is so much more concise than "nums[nums.length()-1]".

3. You can even use the handy "first" and "last" methods.
   ?

   1 2	[1,2,3].last  => 3 [1,2,3].first => 1

4. length

   To get the count, or size, of an array, use the "length" method.

   ?

   1 2	mystuff = ["tivo","nokia", "ipaq"]  # make a string array puts mystuff.length  => 3

5. %w shortcut

   Since many arrays are composed of single words and all those commas and quote marks are troublesome, Ruby provides a handy shortcut, %w:

   ?

   1	mystuff = %w{tivo nokia ipaq}  # make a string array

6. inspect

   To look at contents of an object use the "inspect" method. Even more convenient is to use "p" as a shorthand for "puts obj.inspect"

   ?

   1 2 3 4

   myarray = [1,2,5,7,11] puts myarray puts myarray.inspect p myarray

   Produces:

   1
   2
   5
   7
   11
   [1, 2, 5, 7, 11]
   [1, 2, 5, 7, 11]

7. Arrays can act like queues and sets
   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

   # & is the intersection operator puts [1,2,3] & [3,4,5]  #  prints 3   # + is the addition operator puts [1,2,3]+ [3,4,5]  #  prints 1,2,3,3,4,5   # - removes items from the first array that appear in the second puts [1,2,3] - [3,4,5]  #  prints 1,2   # pop returns the last element and removes it from the array alpha = ["a","b","c","d","e","f"] puts "pop="+alpha.pop   # pop=f puts alpha.inspect      # ["a", "b", "c", "d", "e"]   # push appends elements to the end of an array alpha = ["a","b","c"] alpha.push("x","y","z") puts alpha.inspect      # ["a", "b", "c", "x", "y", "z"]   # shift returns the first element and removes it from the array alpha = ["a","b","c","d","e","f"] puts "shift="+alpha.shift   # shift=a puts alpha.inspect      # ["b", "c", "d", "e", "f"]   # unshift appends elements to the beginning of an array alpha = ["a","b","c"] alpha.unshift("x","y","z") puts alpha.inspect      # ["x", "y", "z", "a", "b", "c"]

Hashes

This type of collection is also called a dictionary or an associative array.

1. Simple hash of cars and their makers
   ?

   1 2 3 4 5 6

   cars = { ‘altima‘ => ‘nissan‘, ‘camry‘ => ‘toyota‘, ‘rx7‘ => ‘mazda‘ } puts cars[‘rx7‘]   =>   mazda

2. You can create a hash and fill it dynamically
   ?

   1 2 3 4 5 6 7 8 9

   dict = {}  # create a new dictionary dict[‘H‘] = ‘Hydrogen‘ #associate the key ‘H‘ to the value ‘Hydrogen‘ dict[‘He‘] = ‘Helium‘ dict[‘Li‘] = ‘Lithium‘ p dict[‘H‘]       # prints "Hydrogen" p dict.length     # prints 3 p dict.values     # prints ["Lithium", "Helium", "Hydrogen"] p dict.keys       # prints ["Li", "He", "H"] p dict            # prints {"Li"=>"Lithium", "He"=>"Helium", "H"=>"Hydrogen"}

3. Hash[]

   You can also create Hashes with square brackets by prefixing with "Hash":

   ?

   1 2	toppings = Hash["pancakes","syrup","Pizza","Pepper","Cereal","Sugar"] puts toppings.inspect

   Produces:

   {"Pizza"=>"Pepper", "Cereal"=>"Sugar", "pancakes"=>"syrup"}

4. each

   The "each" method is a wonderful way to iterate over the keys

   ?

   1 2	toppings = Hash["pancakes","syrup","Pizza","Pepper","Cereal","Sugar"] toppings.each{|key, value| puts "#{key} points to #{value}"}

   Produces:

   Pizza points to Pepper
   Cereal points to Sugar
   pancakes points to syrup
   

5. select

   The "select" method populates a new array with members which meet a criteria

   ?

   1 2 3 4

   salaries = Hash["bob",10.9,"larry",7.5,"jimmy",6.0,"jerry",6.5] salaries.inspect mySalaryArray = salaries.select{|name,salary| salary > 7.0} puts mySalaryArray.inspect #prints  [["larry", 7.5], ["bob", 10.9]]

Ranges

Ranges are composed of expr..expr or expr...expr. Two dots includes the last element, three dots excludes it.

Produces:

a
b
c
d
e
f
g

Produces only two numbers since "..." does not include the last element.:

1
2

Control Statements

1. if 

   ?

   1 2 3 4 5 6

   if 1<2  rate = 0.28 else   rate = 0.5 end puts rate

2. case
   ?

   1 2 3 4 5 6 7 8 9 10 11 12

   grade = 10 school = case grade when 0..5    "elementary" when 6..8    "middle school" when 9..12    "high school" else    "college" end puts "grade #{grade} is in #{school}"

3. for
   ?

   1 2 3

   for i in 1..4  puts "hi #{i}" end

   The ranges can of course have variables

   ?

   1 2 3 4

   top = 6 for i in 1..top  puts "hi #{i}" end

4. exit
   ?

   1 2 3 4 5

   lines = IO.readlines("data.txt") if lines.length < 100    exit 2 end puts lines.length

5. loop

   iterates over code until a "break" or eternity ends

   ?

   1 2 3 4 5 6

   i=0 loop do    break if i > 5    puts i    i += 1  end

Statement modifiers

These are just syntatic sugar.

1. if

   The "if" clause may be placed at the end of a statement

   ?

   1 2	balance = -10.0 puts "Bankrupt" if balance < 0.0

2. unless

   "unless" is placed at the end of a statement

   ?

   1 2	balance = -10.0 puts "Bankrupt" unless balance > 0.0

3. while

   "while" may be after its block

   ?

   1 2 3 4 5 6

   f=2 puts f=f+2 while f < 10 =>4 =>6 =>8 =>10

Iterators

1. while
   ?

   1 2 3 4 5 6

   i = 0 while i  < 5     i = i+1   puts i end

2. "times"
   ?

   1 2	n = 10 n.times { |i| print i}

   Produces:

   0123456789

3. "each"
   ?

   1 2	animals = %w(lions tigers bears) animals.each{|kind| print kind}

   lionstigersbears
   

4. "each" with ranges
   ?

   1	(‘m‘..‘z‘).each {|ch| print ch}

   mnopqrstuvwxyz
   

5. "upto"
   ?

   1 2	n=0 ; max=7 n.upto(max) {|num| print num}

   01234567

You gotta have class.

1. Classes

   Class definitions start with "class" and end with "end". Remember that class names start with a capital letter. Notice the syntax is "object.new" for creating an object and that the "initialize" method contains code normally found in the constructor. Here‘s a small example:

   ?

   1 2 3 4 5 6 7 8

   class Person   def initialize(fname, lname)    @fname = fname    @lname = lname   end end person = Person.new("Augustus","Bondi") print person

   Produces:

   #<Person:0x257c020>
   

   which is true, but not helpful.

2. The "ToString" method, to_s
   ?

   1 2 3 4 5 6 7 8 9 10 11

   class Person   def initialize(fname, lname)    @fname = fname    @lname = lname   end   def to_s      "Person: #@fname #@lname"   end end person = Person.new("Augustus","Bondi") print person

   Produces:

   Person: Augustus Bondi
   

3. Subclassing

   In Ruby subclassing is done with the "<" character

   ?

   1 2 3 4 5 6 7 8 9 10 11

   class Employee < Person   def initialize(fname, lname, position)     super(fname,lname)     @position = position   end   def to_s      super + ", #@position"   end end employee = Employee.new("Augustus","Bondi","CFO") print employee

   Produces:

   Person: Augustus Bondi, CFO
   

   if we try to print the first name directly like

   print employee.fname
   

   we get the error message,

   CFOtest.rb:21: undefined method ‘fname‘

   But why is that? We‘ve printed variables a zillion times up til now and it‘s always worked. What changed? Up until now we‘ve created variables in a program without classes (actually all are variables were members of a default object that were accessable inside itself). Now we are using real classes and that brings up the point of visibility of members outside the class. We now have to specify if a variable is open to the outside, like "public", "private", "protected", "internal" in other languages.

   To grant access to read a variable we declare it after "attr_reader". attribute with the following:

   ?

   1	attr_reader :fname, :lname

   then

   print employee.fname  =>   "Augustus"

   To allow writing to a variable use "attr_writer",

   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

   class Employee < Person   def initialize(fname, lname, position)     super(fname,lname)     @position = position   end   def to_s      super + ", #@position"   end   attr_writer :position end employee = Employee.new("Augustus","Bondi","CFO") puts employee puts employee.fname employee.position = "CEO" puts employee

Virtual Attributes

Regular Expressions

Strings can be compared to a regular expression with "=~". Regular expressions are surrounded by "//" or "%r{}". Anything but the two special values, "false" and "nil" are considered true.

Blocks

And now to one of the coolest things about Ruby - blocks. Blocks are nameless chunks of code that may be passed as an argument to a function.

Simple Example

Produces:

where is the money?
where is the money?
where is the money?

In the above example ‘{puts "where is the money?"}‘ is called a block. That chunk of code is passed to the method "whereisit" and executed each time the "yield" statement is executed. You can think of the "yield" being replaced by the block of code.

Blocks can take arguments

Here the method "cubes" takes the max value.

Think of the "yield i**3" in the function cubes as being replaced with the block, ‘|x| print x, ", "‘. The value following the "yield" is passed as the value "x" to the block.

Multiple arguments may be passed to blocks.

Produces:

employee : Milo Croton

Local variables can be shared with a block

Even though rate is a local variable, it is used inside the block.

Produces:

tip should be: 1.5

Blocks are built in to many objects in ruby

each

iterates through each item of a collection

Produces:

1 4 9 16

detect

returns the first item matching a logical expression

select

returns all items matching a logical expression

collect

returns an array created by doing the operation on each element.

inject

"inject" is the "fold" or "reducer" function in Ruby. "inject" loops over an enumerable and performs an operation on each object and returns a single value.

File I/O

1. Read an entire file into a string
   ?

   1 2	file = File.new( "t1.php" ) mytext = file.read

2. Read an entire file into an array of lines
   ?

   1 2	lines = IO.readlines("data.txt") puts lines[0]  #prints the first line

3. Read a file line by line
   ?

   1 2 3 4

   file = File.open("res.txt") while line = file.gets    puts line end

   Or you can use the IO class

   ?

   1	IO.foreach("data.txt") { |line| puts line }

4. Read a file line by line

   You should ensure the file is closed as well.

   ?

   1 2 3 4 5 6 7 8

   begin file = File.open("res.txt")    while line = file.gets       puts line    end ensure    file.close end

5. Read only a few bytes at a time

   The following snippet of code reads a file which may have no line breaks and chops it into 80 character lines

   ?

   1 2 3 4 5 6

   require ‘readbytes‘ file = File.new( "C:/installs/myapp_log.xml" ) while bytes = file.readbytes(80)    print bytes+"\r\n" end file.close

6. Reads a large XML file and inserts line breaks

   Uses TruncatedDataError to grab the last few slacker bytes from the end.

   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14

   # reads an xml file without line breaks and puts a line break before each ‘<‘ require ‘readbytes‘ file = File.new( "C:/installs/SurveyDirector_log.xml" ) begin    while bytes = file.readbytes(80)       print bytes.gsub(/</,"\r\n<")    end rescue TruncatedDataError #the last read had less chars than specified    #print the rest of the data.  $! is the exception.    # ".data" has the extra bytes    print $!.data.gsub(/</,"\r\n<") ensure    file.close unless file.nil? end

7. method_missing - a wonderful idea

   In most languages when a method cannot be found and error is thrown and your program stops. In ruby you can actually catch those errors and perhaps do something intelligent with the situation. A trivial example:

   ?

   1 2 3 4 5 6 7 8 9 10 11

   class MathWiz   def add(a,b)     return a+b   end   def method_missing(name, *args)     puts "I don‘t know the method #{name}"   end end mathwiz = MathWiz.new puts mathwiz.add(1,4) puts mathwiz.subtract(4,2)

   Produces:

   5
   I don‘t know the method subtract
   nil

8. While the ruby program is loading, you can execute code inside a special block labeled "BEGIN" - pretty nifty. After the interpretor has loaded the code, but before execution, you can execute code in the "END" block.

   ?

   1 2 3 4 5 6 7

   puts "main program running" END { puts "program ending" } BEGIN { puts "I‘m loading" }

   Produces:

   I‘m loading
   main program running
   program ending
   

9. converting between strings and ints

   Use the to_i and to_s methods

   ?

   1 2	"3".to_i  #return an integer 3.to_s    # returns a string

Using XML Dom Parser

REXML goes standard with Ruby 1.8. Sample to print all "div" elements whose "class" attribute is set to "entry".

Run a few lines directly from the command line with the "-e" option

c:\home\mfincher>ruby -e ‘sleep 2‘
c:\home\mfincher>ruby -e ‘puts 3*4‘
12
c:\home\mfincher>ruby -e ‘puts 3*4; puts 4*4‘
12
16

1. Editing files in place

   Ruby offers a simple way to make a string substitution in many files all at once with a single line of code. The "-p" option loops over the files, the "-i" is the backup extension. With this command we are changing all the documentation from version 1.5 to 1.6, but the original files are renamed to ".bak".

   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

   C:\home\mfincher\ruby>more v2.txt Regarding version 1.5 ... .... version 1.5 is easy to install   C:\home\mfincher\ruby>ruby -pi.bak -e "gsub(/1.5/,‘1.6‘)" v*.txt   C:\home\mfincher\ruby>more v2.txt Regarding version 1.6 ... .... version 1.6 is easy to install   C:\home\mfincher\ruby>more v2.txt.bak Regarding version 1.5 ... .... version 1.5 is easy to install

2. Example of printing duplicate lines in sorted file.
   ?

   1 2 3 4 5 6 7 8 9 10 11 12

   #prints duplicate lines in sorted files in the file passed in as first arg file = File.open(ARGV[0]) lastLine = "" counter = 0    while line = file.gets         counter += 1     if lastLine == line            puts "#{counter-1}: #{line}#{counter}: #{line}\r\n"         end     lastLine = line    end puts "done. Processed #{counter} lines"

3. Ruby has its own interpreted shell, irb.
   ?

   1 2 3 4 5 6 7 8 9

   C:\home\mfincher>irb irb(main):001:0> puts "Hello World" Hello World => nil irb(main):002:0> a=1 => 1 irb(main):003:0> a*2 => 2 irb(main):004:0>

4. ruby can take input from stdin
   ?

   1	echo ‘puts "hello"‘ | ruby

5. to pass a string on the url it needs to be "escape"‘d first.
   ?

   1 2 3

   require ‘uri‘ ... URI.escape("some string...")

Example to remove "funny" characters from a filename

Example of iterating over the filenames in a directory, using regular expression substitution in strings, and renaming files.

Looping over list of arguments

Miscellanous Commands

Interesting string functions

DateTime

Using ‘require‘

require will let your access code from other files. ‘require‘ looks in directories specified in $LOAD_PATH to find the files. The environmental variable RUBYLIB can be used to load paths into $LOAD_PATH.

You can put a library like ‘startClicker.rb‘ in any of those directories and ruby will find it.

BuiltIn Command Interpreter

With the "eval" method you can create your own interpreter language and run it during execution.

Introspection with ObjectSpace

You can find all the objects in your program of a particular type using ObjectSpace.each_object.

Produces:

Janie
Alfred

Testing

Ruby comes right out of the box with a testing framework. Here‘s a quick example:

Read a URL and print the web page to the screen.

This will get a particular page and print to the screen:

This will read a file of urls and print all to the screen:

Example of drawing a line on a canvas in Tk

Tk is a graphical subsystem used in languages like Perl and Tcl.

irb - interactive ruby

Ruby comes with an REPL (Read Eval Print Loop) utility to let you try ruby interactively. ("inf-ruby.el" provides an internal shell in emacs for irb).

RubyGems a ruby package installer

You can download RubyGems from http://rubyforge.org. Unzip the files (eg, C:\opt\ruby) then install by entering:

C:>cd C:\opt\ruby\rubygems-0.9.0
C:\opt\ruby\rubygems-0.9.0>ruby setup.rb all

Ruby on Rails

How to write a log message

You can use logger‘s methods "warn", "info", "error", and "fatal".

Field names ending with "_at" are assumed to be datetime fields and are filled in automagically by rails for ActiveRecord objects. The suffix "_on" are assumed to be dates.

Console

to dubug applications it‘s convenient to use the console script

myapp>ruby script/console

debug method

You can use the debug() method inside web pages to dump info about an object.

<p>Thanks for visiting</p>
<%= debug(@myobject) %>

How to Freeze a version

Since your hosting company may upgrade the rails version you need to "freeze" the current version. The following copies all the 1.2.6 libraries from the shared directory to your own private one.

rake rails:freeze:edge TAG=rel_1-2-6

Active record notes

1. Find all records meeting a criteria

   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

   def self.suitable_jokes(sort_key) if sort_key == "Newest"    find(:all,         :conditions => "suitable  = \"1\"",         :order => "entry_date DESC"        ) elsif sort_key == "Worst"    find(:all,         :conditions => "suitable  = \"1\"",         :order => "entry_date ASC"        ) else    find(:all,         :conditions => "suitable  = \"1\"",         :order => "current_rating DESC"        ) end end

   The first argument to find can also be ":first" or ":last".

2. Find the count of records meeting a criteria
   ?

   1 2 3 4 5 6

   def self.waiting_jokes()   count("suitable  = \"0\"") end def self.total()   count("suitable  = \"1\"") end

   Find the total number of items

   ?

   1	count = Joke.count

   Find the total number of items meeting a criteria

   ?

   1	count = Joke.count(["suitable = \"1\""])

3. Pagination

   The ":limit" and ":offset" options allow easy pagination.

   To return the fifth page of items use the following:

   ?

   1 2 3 4 5 6

   find(:all,         :conditions => "suitable  = \"1\"",         :order => "current_rating DESC",     :limit => 10,     :offset => 40        )

4. Use raw SQL and return two values
   ?

   1 2 3 4

   def getAverageRatingAndCount     record = Rating.find_by_sql(["select count(*) as count,avg(rating) as average from ratings WHERE joke_id = ?",id]);     return record[0].average.to_f , record[0].count.to_i end

5. The "create" method in ActiveRecord will do "new" and "save" operations simultanously.
   ?

   1 2 3 4

   mydog = Dog.create( :name => "Fido" :breed => "Collie" )

Watir

Watir is a GUI testing tool written in Ruby. Here is a script to open Google and search for pictures of kittens.

1. Selecting a JavaScript popup box

   stolen from http://wiki.openqa.org/display/WTR/FAQ

   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

   #Watir script to show clicking a JavaScript popup box require "watir" require ‘watir\contrib\enabled_popup‘ require ‘startClicker‘ require ‘net/http‘ require ‘net/https‘   $ie = Watir::IE.new  #create an object to drive the browser $ie.goto "http://mydomain.com/ListGroups.aspx" if $ie.contains_text("Log In")   $ie.text_field(:name, "Login1$UserName").set("fincherm")   $ie.text_field(:name, "Login1$Password").set("mitch")   $ie.button(:name, "Login1$LoginButton").click end $ie.link(:text, "Baseline").click $ie.link(:text, "MoonManC").click def setDdlPriority(priority)    ddlPriority = $ie.select_list( :name , /ddlPriority/)    puts ddlPriority    ddlPriority.select(priority)    puts ddlPriority    $ie.button(:name, "ctl00$btnSave").click_no_wait       startClicker( "OK", 4 , "User Input" )       sleep 1   end setDdlPriority("2") setDdlPriority("9")

   　　

   startClicker.rb:

   ?

   1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

   #method startClicker from http://wiki.openqa.org/display/WTR/FAQ def startClicker( button , waitTime= 9, user_input=nil )   # get a handle if one exists   hwnd = $ie.enabled_popup(waitTime)    if (hwnd)  # yes there is a popup     w = WinClicker.new     if ( user_input )       w.setTextValueForFileNameField( hwnd, "#{user_input}" )     end     # I put this in to see the text being input it is not necessary to work     sleep 3             # "OK" or whatever the name on the button is     w.clickWindowsButton_hwnd( hwnd, "#{button}" )     #     # this is just cleanup     w=nil      end end

   　　

   1. How to use Watir with NUnit

      Here is an example of connecting it to NUnit.

      ?

      1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

      using System; using System.Diagnostics; using System.Text.RegularExpressions; using NUnit.Framework;   namespace SurveyDirector.Test.Watir {     /// <summary>     /// from http://www.hanselman.com/blog/IntegratingRubyAndWatirWithNUnit.aspx/// with small hacks from Liz Buenker     /// </summary>     public classWatirAssert     {         public static void TestPassed(string rubyFileName, string directoryPath)         {             string output = String.Empty;             using (Process p = new Process())             {                 p.StartInfo.UseShellExecute = false;                 p.StartInfo.RedirectStandardOutput = true;                 p.StartInfo.FileName = "ruby.exe";                 p.StartInfo.Arguments = rubyFileName + " -b";                 p.StartInfo.WorkingDirectory = directoryPath;                 p.Start();                 output = p.StandardOutput.ReadToEnd();                 p.WaitForExit();             }             Console.Write(output);             Trace.Write(output);             Regex reg = new Regex(@"(?<tests>\d+) tests, (?<assertions>\d+) assertions, (?<failures>\d+) failures, (?<errors>\d+) errors", RegexOptions.Compiled);             Match m = reg.Match(output);             try             {                 int tests = int.Parse(m.Groups["tests"].Value);                 int assertions = int.Parse(m.Groups["assertions"].Value);                 int failures = int.Parse(m.Groups["failures"].Value);                 int errors = int.Parse(m.Groups["errors"].Value);                 if (tests > 0 && failures > 0)                 {                     Assert.Fail(String.Format("WatirAssert: Failures {0}", failures));                 }                 else if (errors > 0)                 {                     Assert.Fail(String.Format("WatirAssert: Errors {0}", errors));                 }             }             catch (Exception e)             {                 Assert.Fail("WatirAssert EXCEPTION: " + e.ToString());             }         }     } }

      　　

      The above code would be used by something like this:

      ?

      1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

      using System; using NUnit.Framework;   namespace SurveyDirector.Test.Watir {     [TestFixture]     public classWatirTest     {         private static readonly string testDir = Utilities.Properties.baseDir + "\\Test\\Watir";         public WatirTest() { }         [Test]         public void Sd01Test()         {             WatirAssert.TestPassed("sd01_test.rb",testDir);         }         [Test]         public void Sd02Test()         {             WatirAssert.TestPassed("sd02_test.rb",testDir);         }       } }

      　　

2. Ruby Quotes:

   
   "Ruby is a language for clever people." -Matz 
   "Ruby is the perlification of Lisp." -Matz 
   "Type Declarations are the Maginot line of programming." -Mitch Fincher