Raised by exit to initiate the termination of the script.
Raised when the interrupt signal is received, typically because the user has pressed Control-C (on most posix platforms). As such, it is a subclass of SignalException.
begin puts "Press ctrl-C when you get bored" loop {} rescue Interrupt => e puts "Note: You will typically use Signal.trap instead." end
produces:
Press ctrl-C when you get bored
then waits until it is interrupted with Control-C and then prints:
Note: You will typically use Signal.trap instead.
The most standard error types are subclasses of StandardError. A rescue clause without an explicit Exception class will rescue all StandardErrors (and only those).
def foo raise "Oups" end foo rescue "Hello" #=> "Hello"
On the other hand:
require 'does/not/exist' rescue "Hi"
raises the exception:
LoadError: no such file to load -- does/not/exist
Raised when the given index is invalid.
a = [:foo, :bar] a.fetch(0) #=> :foo a[4] #=> nil a.fetch(4) #=> IndexError: index 4 outside of array bounds: -2...2
Raised when a given numerical value is out of range.
[1, 2, 3].drop(1 << 100)
raises the exception:
RangeError: bignum too big to convert into `long'
ScriptError is the superclass for errors raised when a script can not be executed because of a LoadError, NotImplementedError or a SyntaxError. Note these type of ScriptErrors are not StandardError and will not be rescued unless it is specified explicitly (or its ancestor Exception).
Raised when attempting a potential unsafe operation, typically when the $SAFE level is raised above 0.
foo = "bar" proc = Proc.new do $SAFE = 3 foo.untaint end proc.call
raises the exception:
SecurityError: Insecure: Insecure operation `untaint' at level 3
SystemCallError is the base class for all low-level platform-dependent errors.
The errors available on the current platform are subclasses of SystemCallError and are defined in the Errno module.
File.open("does/not/exist")
raises the exception:
Errno::ENOENT: No such file or directory - does/not/exist
A Range represents an interval—a set of values with a beginning and an end. Ranges may be constructed using the s..e and s...e literals, or with Range::new. Ranges constructed using .. run from the beginning to the end inclusively. Those created using ... exclude the end value. When used as an iterator, ranges return each value in the sequence.
(-1..-5).to_a #=> [] (-5..-1).to_a #=> [-5, -4, -3, -2, -1] ('a'..'e').to_a #=> ["a", "b", "c", "d", "e"] ('a'...'e').to_a #=> ["a", "b", "c", "d"]
An “endless range” represents a semi-infinite range. Literal notation for an endless range is:
(1..) # or similarly (1...)
Which is equivalent to
(1..nil) # or similarly (1...nil) Range.new(1, nil) # or Range.new(1, nil, true)
Endless ranges are useful, for example, for idiomatic slicing of arrays:
[1, 2, 3, 4, 5][2...] # => [3, 4, 5]
Some implementation details:
end of endless range is nil;
each of endless range enumerates infinite sequence (may be useful in combination with Enumerable#take_while or similar methods);
(1..) and (1...) are not equal, although technically representing the same sequence.
Ranges can be constructed using any objects that can be compared using the <=> operator. Methods that treat the range as a sequence (each and methods inherited from Enumerable) expect the begin object to implement a succ method to return the next object in sequence. The step and include? methods require the begin object to implement succ or to be numeric.
In the Xs class below both <=> and succ are implemented so Xs can be used to construct ranges. Note that the Comparable module is included so the == method is defined in terms of <=>.
class Xs # represent a string of 'x's include Comparable attr :length def initialize(n) @length = n end def succ Xs.new(@length + 1) end def <=>(other) @length <=> other.length end def to_s sprintf "%2d #{inspect}", @length end def inspect 'x' * @length end end
An example of using Xs to construct a range:
r = Xs.new(3)..Xs.new(6) #=> xxx..xxxxxx r.to_a #=> [xxx, xxxx, xxxxx, xxxxxx] r.member?(Xs.new(5)) #=> true
Ripper is a Ruby script parser.
You can get information from the parser with event-based style. Information such as abstract syntax trees or simple lexical analysis of the Ruby program.
Ripper provides an easy interface for parsing your program into a symbolic expression tree (or S-expression).
Understanding the output of the parser may come as a challenge, it’s recommended you use PP to format the output for legibility.
require 'ripper'
require 'pp'
pp Ripper.sexp('def hello(world) "Hello, #{world}!"; end')
#=> [:program,
[[:def,
[:@ident, "hello", [1, 4]],
[:paren,
[:params, [[:@ident, "world", [1, 10]]], nil, nil, nil, nil, nil, nil]],
[:bodystmt,
[[:string_literal,
[:string_content,
[:@tstring_content, "Hello, ", [1, 18]],
[:string_embexpr, [[:var_ref, [:@ident, "world", [1, 27]]]]],
[:@tstring_content, "!", [1, 33]]]]],
nil,
nil,
nil]]]]
You can see in the example above, the expression starts with :program.
From here, a method definition at :def, followed by the method’s identifier :@ident. After the method’s identifier comes the parentheses :paren and the method parameters under :params.
Next is the method body, starting at :bodystmt (stmt meaning statement), which contains the full definition of the method.
In our case, we’re simply returning a String, so next we have the :string_literal expression.
Within our :string_literal you’ll notice two @tstring_content, this is the literal part for Hello, and !. Between the two @tstring_content statements is a :string_embexpr, where embexpr is an embedded expression. Our expression consists of a local variable, or var_ref, with the identifier (@ident) of world.
ruby 1.9 (support CVS HEAD only)
bison 1.28 or later (Other yaccs do not work)
Ruby License.
Minero Aoki
aamine@loveruby.net
WIN32OLE objects represent OLE Automation object in Ruby.
By using WIN32OLE, you can access OLE server like VBScript.
Here is sample script.
require 'win32ole' excel = WIN32OLE.new('Excel.Application') excel.visible = true workbook = excel.Workbooks.Add(); worksheet = workbook.Worksheets(1); worksheet.Range("A1:D1").value = ["North","South","East","West"]; worksheet.Range("A2:B2").value = [5.2, 10]; worksheet.Range("C2").value = 8; worksheet.Range("D2").value = 20; range = worksheet.Range("A1:D2"); range.select chart = workbook.Charts.Add; workbook.saved = true; excel.ActiveWorkbook.Close(0); excel.Quit();
Unfortunately, Win32OLE doesn’t support the argument passed by reference directly. Instead, Win32OLE provides WIN32OLE::ARGV or WIN32OLE_VARIANT object. If you want to get the result value of argument passed by reference, you can use WIN32OLE::ARGV or WIN32OLE_VARIANT.
oleobj.method(arg1, arg2, refargv3) puts WIN32OLE::ARGV[2] # the value of refargv3 after called oleobj.method
or
refargv3 = WIN32OLE_VARIANT.new(XXX, WIN32OLE::VARIANT::VT_BYREF|WIN32OLE::VARIANT::VT_XXX) oleobj.method(arg1, arg2, refargv3) p refargv3.value # the value of refargv3 after called oleobj.method.
Raised when OLE processing failed.
EX:
obj = WIN32OLE.new("NonExistProgID")
raises the exception:
WIN32OLERuntimeError: unknown OLE server: `NonExistProgID'
HRESULT error code:0x800401f3
Invalid class string
Outputs a source level execution trace of a Ruby program.
It does this by registering an event handler with Kernel#set_trace_func for processing incoming events. It also provides methods for filtering unwanted trace output (see Tracer.add_filter, Tracer.on, and Tracer.off).
Consider the following Ruby script
class A def square(a) return a*a end end a = A.new a.square(5)
Running the above script using ruby -r tracer example.rb will output the following trace to STDOUT (Note you can also explicitly require 'tracer')
#0:<internal:lib/rubygems/custom_require>:38:Kernel:<: - #0:example.rb:3::-: class A #0:example.rb:3::C: class A #0:example.rb:4::-: def square(a) #0:example.rb:7::E: end #0:example.rb:9::-: a = A.new #0:example.rb:10::-: a.square(5) #0:example.rb:4:A:>: def square(a) #0:example.rb:5:A:-: return a*a #0:example.rb:6:A:<: end | | | | | | | | | ---------------------+ event | | | ------------------------+ class | | --------------------------+ line | ------------------------------------+ filename ---------------------------------------+ thread
Symbol table used for displaying incoming events:
call a C-language routine
return from a C-language routine
call a Ruby method
C
start a class or module definition
E
finish a class or module definition
-
execute code on a new line
raise an exception
return from a Ruby method
by Keiju ISHITSUKA(keiju@ishitsuka.com)
The GetoptLong class allows you to parse command line options similarly to the GNU getopt_long() C library call. Note, however, that GetoptLong is a pure Ruby implementation.
GetoptLong allows for POSIX-style options like --file as well as single letter options like -f
The empty option -- (two minus symbols) is used to end option processing. This can be particularly important if options have optional arguments.
Here is a simple example of usage:
require 'getoptlong' opts = GetoptLong.new( [ '--help', '-h', GetoptLong::NO_ARGUMENT ], [ '--repeat', '-n', GetoptLong::REQUIRED_ARGUMENT ], [ '--name', GetoptLong::OPTIONAL_ARGUMENT ] ) dir = nil name = nil repetitions = 1 opts.each do |opt, arg| case opt when '--help' puts <<-EOF hello [OPTION] ... DIR -h, --help: show help --repeat x, -n x: repeat x times --name [name]: greet user by name, if name not supplied default is John DIR: The directory in which to issue the greeting. EOF when '--repeat' repetitions = arg.to_i when '--name' if arg == '' name = 'John' else name = arg end end end if ARGV.length != 1 puts "Missing dir argument (try --help)" exit 0 end dir = ARGV.shift Dir.chdir(dir) for i in (1..repetitions) print "Hello" if name print ", #{name}" end puts end
Example command line:
hello -n 6 --name -- /tmp
The set of all prime numbers.
Prime.each(100) do |prime| p prime #=> 2, 3, 5, 7, 11, ...., 97 end
Prime is Enumerable:
Prime.first 5 # => [2, 3, 5, 7, 11]
For convenience, each instance method of Prime.instance can be accessed as a class method of Prime.
e.g.
Prime.instance.prime?(2) #=> true Prime.prime?(2) #=> true
A “generator” provides an implementation of enumerating pseudo-prime numbers and it remembers the position of enumeration and upper bound. Furthermore, it is an external iterator of prime enumeration which is compatible with an Enumerator.
Prime::PseudoPrimeGenerator is the base class for generators. There are few implementations of generator.
Prime::EratosthenesGenerator
Uses eratosthenes’ sieve.
Prime::TrialDivisionGenerator
Uses the trial division method.
Prime::Generator23
Generates all positive integers which are not divisible by either 2 or 3. This sequence is very bad as a pseudo-prime sequence. But this is faster and uses much less memory than the other generators. So, it is suitable for factorizing an integer which is not large but has many prime factors. e.g. for Prime#prime? .
PStore implements a file based persistence mechanism based on a Hash. User code can store hierarchies of Ruby objects (values) into the data store file by name (keys). An object hierarchy may be just a single object. User code may later read values back from the data store or even update data, as needed.
The transactional behavior ensures that any changes succeed or fail together. This can be used to ensure that the data store is not left in a transitory state, where some values were updated but others were not.
Behind the scenes, Ruby objects are stored to the data store file with Marshal. That carries the usual limitations. Proc objects cannot be marshalled, for example.
require "pstore" # a mock wiki object... class WikiPage def initialize( page_name, author, contents ) @page_name = page_name @revisions = Array.new add_revision(author, contents) end attr_reader :page_name def add_revision( author, contents ) @revisions << { :created => Time.now, :author => author, :contents => contents } end def wiki_page_references [@page_name] + @revisions.last[:contents].scan(/\b(?:[A-Z]+[a-z]+){2,}/) end # ... end # create a new page... home_page = WikiPage.new( "HomePage", "James Edward Gray II", "A page about the JoysOfDocumentation..." ) # then we want to update page data and the index together, or not at all... wiki = PStore.new("wiki_pages.pstore") wiki.transaction do # begin transaction; do all of this or none of it # store page... wiki[home_page.page_name] = home_page # ensure that an index has been created... wiki[:wiki_index] ||= Array.new # update wiki index... wiki[:wiki_index].push(*home_page.wiki_page_references) end # commit changes to wiki data store file ### Some time later... ### # read wiki data... wiki.transaction(true) do # begin read-only transaction, no changes allowed wiki.roots.each do |data_root_name| p data_root_name p wiki[data_root_name] end end
By default, file integrity is only ensured as long as the operating system (and the underlying hardware) doesn’t raise any unexpected I/O errors. If an I/O error occurs while PStore is writing to its file, then the file will become corrupted.
You can prevent this by setting pstore.ultra_safe = true. However, this results in a minor performance loss, and only works on platforms that support atomic file renames. Please consult the documentation for ultra_safe for details.
Needless to say, if you’re storing valuable data with PStore, then you should backup the PStore files from time to time.
Raised when attempting to convert special float values (in particular Infinity or NaN) to numerical classes which don’t support them.
Float::INFINITY.to_r #=> FloatDomainError: Infinity
The global value true is the only instance of class TrueClass and represents a logically true value in boolean expressions. The class provides operators allowing true to be used in logical expressions.
ConditionVariable objects augment class Mutex. Using condition variables, it is possible to suspend while in the middle of a critical section until a resource becomes available.
Example:
mutex = Mutex.new resource = ConditionVariable.new a = Thread.new { mutex.synchronize { # Thread 'a' now needs the resource resource.wait(mutex) # 'a' can now have the resource } } b = Thread.new { mutex.synchronize { # Thread 'b' has finished using the resource resource.signal } }
This module provides a framework for message digest libraries.
You may want to look at OpenSSL::Digest as it supports more algorithms.
A cryptographic hash function is a procedure that takes data and returns a fixed bit string: the hash value, also known as digest. Hash functions are also called one-way functions, it is easy to compute a digest from a message, but it is infeasible to generate a message from a digest.
require 'digest' # Compute a complete digest Digest::SHA256.digest 'message' #=> "\xABS\n\x13\xE4Y..." sha256 = Digest::SHA256.new sha256.digest 'message' #=> "\xABS\n\x13\xE4Y..." # Other encoding formats Digest::SHA256.hexdigest 'message' #=> "ab530a13e459..." Digest::SHA256.base64digest 'message' #=> "q1MKE+RZFJgr..." # Compute digest by chunks md5 = Digest::MD5.new md5.update 'message1' md5 << 'message2' # << is an alias for update md5.hexdigest #=> "94af09c09bb9..." # Compute digest for a file sha256 = Digest::SHA256.file 'testfile' sha256.hexdigest
Additionally digests can be encoded in “bubble babble” format as a sequence of consonants and vowels which is more recognizable and comparable than a hexadecimal digest.
require 'digest/bubblebabble' Digest::SHA256.bubblebabble 'message' #=> "xopoh-fedac-fenyh-..."
See the bubble babble specification at web.mit.edu/kenta/www/one/bubblebabble/spec/jrtrjwzi/draft-huima-01.txt.
Digest algorithms Different digest algorithms (or hash functions) are available:
MD5
See RFC 1321 The MD5 Message-Digest Algorithm
As Digest::RMD160. See homes.esat.kuleuven.be/~bosselae/ripemd160.html.
SHA1
See FIPS 180 Secure Hash Standard.
See FIPS 180 Secure Hash Standard which defines the following algorithms:
SHA512
SHA384
SHA256
The latest versions of the FIPS publications can be found here: csrc.nist.gov/publications/PubsFIPS.html.
The Readline module provides interface for GNU Readline. This module defines a number of methods to facilitate completion and accesses input history from the Ruby interpreter. This module supported Edit Line(libedit) too. libedit is compatible with GNU Readline.
Reads one inputted line with line edit by Readline.readline method. At this time, the facilitatation completion and the key bind like Emacs can be operated like GNU Readline.
require "readline" while buf = Readline.readline("> ", true) p buf end
The content that the user input can be recorded to the history. The history can be accessed by Readline::HISTORY constant.
require "readline" while buf = Readline.readline("> ", true) p Readline::HISTORY.to_a print("-> ", buf, "\n") end
Documented by Kouji Takao <kouji dot takao at gmail dot com>.
FileTest implements file test operations similar to those used in File::Stat. It exists as a standalone module, and its methods are also insinuated into the File class. (Note that this is not done by inclusion: the interpreter cheats).