Results for: "OptionParser"

Cleared reference exception

Scan scalars for built in types

Subclass of Zlib::Error. This error is raised when the zlib stream is currently in progress.

For example:

inflater = Zlib::Inflate.new
inflater.inflate(compressed) do
  inflater.inflate(compressed) # Raises Zlib::InProgressError
end

Overview

This file provides the CGI::Session class, which provides session support for CGI scripts. A session is a sequence of HTTP requests and responses linked together and associated with a single client. Information associated with the session is stored on the server between requests. A session id is passed between client and server with every request and response, transparently to the user. This adds state information to the otherwise stateless HTTP request/response protocol.

Lifecycle

A CGI::Session instance is created from a CGI object. By default, this CGI::Session instance will start a new session if none currently exists, or continue the current session for this client if one does exist. The new_session option can be used to either always or never create a new session. See new() for more details.

delete() deletes a session from session storage. It does not however remove the session id from the client. If the client makes another request with the same id, the effect will be to start a new session with the old session’s id.

Setting and retrieving session data.

The Session class associates data with a session as key-value pairs. This data can be set and retrieved by indexing the Session instance using ‘[]’, much the same as hashes (although other hash methods are not supported).

When session processing has been completed for a request, the session should be closed using the close() method. This will store the session’s state to persistent storage. If you want to store the session’s state to persistent storage without finishing session processing for this request, call the update() method.

Storing session state

The caller can specify what form of storage to use for the session’s data with the database_manager option to CGI::Session::new. The following storage classes are provided as part of the standard library:

CGI::Session::FileStore

stores data as plain text in a flat file. Only works with String data. This is the default storage type.

CGI::Session::MemoryStore

stores data in an in-memory hash. The data only persists for as long as the current Ruby interpreter instance does.

CGI::Session::PStore

stores data in Marshalled format. Provided by cgi/session/pstore.rb. Supports data of any type, and provides file-locking and transaction support.

Custom storage types can also be created by defining a class with the following methods:

new(session, options)
restore  # returns hash of session data.
update
close
delete

Changing storage type mid-session does not work. Note in particular that by default the FileStore and PStore session data files have the same name. If your application switches from one to the other without making sure that filenames will be different and clients still have old sessions lying around in cookies, then things will break nastily!

Maintaining the session id.

Most session state is maintained on the server. However, a session id must be passed backwards and forwards between client and server to maintain a reference to this session state.

The simplest way to do this is via cookies. The CGI::Session class provides transparent support for session id communication via cookies if the client has cookies enabled.

If the client has cookies disabled, the session id must be included as a parameter of all requests sent by the client to the server. The CGI::Session class in conjunction with the CGI class will transparently add the session id as a hidden input field to all forms generated using the CGI#form() HTML generation method. No built-in support is provided for other mechanisms, such as URL re-writing. The caller is responsible for extracting the session id from the session_id attribute and manually encoding it in URLs and adding it as a hidden input to HTML forms created by other mechanisms. Also, session expiry is not automatically handled.

Examples of use

Setting the user’s name

require 'cgi'
require 'cgi/session'
require 'cgi/session/pstore'     # provides CGI::Session::PStore

cgi = CGI.new("html4")

session = CGI::Session.new(cgi,
    'database_manager' => CGI::Session::PStore,  # use PStore
    'session_key' => '_rb_sess_id',              # custom session key
    'session_expires' => Time.now + 30 * 60,     # 30 minute timeout
    'prefix' => 'pstore_sid_')                   # PStore option
if cgi.has_key?('user_name') and cgi['user_name'] != ''
    # coerce to String: cgi[] returns the
    # string-like CGI::QueryExtension::Value
    session['user_name'] = cgi['user_name'].to_s
elsif !session['user_name']
    session['user_name'] = "guest"
end
session.close

Creating a new session safely

require 'cgi'
require 'cgi/session'

cgi = CGI.new("html4")

# We make sure to delete an old session if one exists,
# not just to free resources, but to prevent the session
# from being maliciously hijacked later on.
begin
    session = CGI::Session.new(cgi, 'new_session' => false)
    session.delete
rescue ArgumentError  # if no old session
end
session = CGI::Session.new(cgi, 'new_session' => true)
session.close

Note: Don’t use this class directly. This is an internal class.

The DidYouMean::Formatter is the basic, default formatter for the gem. The formatter responds to the message_for method and it returns a human readable string.

Error raised by the DRb module when an attempt is made to refer to the context’s current drb server but the context does not have one. See current_server.

Class representing a drb server instance.

A DRbServer must be running in the local process before any incoming dRuby calls can be accepted, or any local objects can be passed as dRuby references to remote processes, even if those local objects are never actually called remotely. You do not need to start a DRbServer in the local process if you are only making outgoing dRuby calls passing marshalled parameters.

Unless multiple servers are being used, the local DRbServer is normally started by calling DRb.start_service.

Timer id conversion keeps objects alive for a certain amount of time after their last access. The default time period is 600 seconds and can be changed upon initialization.

To use TimerIdConv:

DRb.install_id_conv TimerIdConv.new 60 # one minute

The table of LALR actions. Actions are either of Shift, Reduce, Accept and Error.

A RingServer allows a Rinda::TupleSpace to be located via UDP broadcasts. Default service location uses the following steps:

1. A RingServer begins listening on the network broadcast UDP address.

2. A RingFinger sends a UDP packet containing the DRb URI where it will listen for a reply.

3. The RingServer receives the UDP packet and connects back to the provided DRb URI with the DRb service.

A RingServer requires a TupleSpace:

ts = Rinda::TupleSpace.new
rs = Rinda::RingServer.new

RingServer can also listen on multicast addresses for announcements. This allows multiple RingServers to run on the same host. To use network broadcast and multicast:

ts = Rinda::TupleSpace.new
rs = Rinda::RingServer.new ts, %w[Socket::INADDR_ANY, 239.0.0.1 ff02::1]

BasicSpecification is an abstract class which implements some common code used by both Specification and StubSpecification.

The Specification class contains the information for a gem. Typically defined in a .gemspec file or a Rakefile, and looks like this:

Gem::Specification.new do |s|
  s.name        = 'example'
  s.version     = '0.1.0'
  s.licenses    = ['MIT']
  s.summary     = "This is an example!"
  s.description = "Much longer explanation of the example!"
  s.authors     = ["Ruby Coder"]
  s.email       = 'rubycoder@example.com'
  s.files       = ["lib/example.rb"]
  s.homepage    = 'https://rubygems.org/gems/example'
  s.metadata    = { "source_code_uri" => "https://github.com/example/example" }
end

Starting in RubyGems 2.0, a Specification can hold arbitrary metadata. See metadata for restrictions on the format and size of metadata items you may add to a specification.

Gem::StubSpecification reads the stub: line from the gemspec. This prevents us having to eval the entire gemspec in order to find out certain information.