A pointer to a C structure
Raised when OLE processing failed.
EX:
obj = WIN32OLE.new("NonExistProgID")
raises the exception:
WIN32OLE::RuntimeError: unknown OLE server: `NonExistProgID'
HRESULT error code:0x800401f3
Invalid class string
Subclass of Zlib::Error
When zlib returns a Z_VERSION_ERROR, usually if the zlib library version is incompatible with the version assumed by the caller.
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.
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.
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.
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!
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.
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
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
Response class for Continue responses (status code 100).
A Continue response indicates that the server has received the request headers.
References:
Response class for Partial Content responses (status code 206).
The Partial Content response indicates that the server is delivering only part of the resource (byte serving) due to a Range header in the request.
References:
Response class for Conflict responses (status code 409).
The request could not be processed because of conflict in the current state of the resource.
References:
Response class for HTTP Version Not Supported responses (status code 505).
The server does not support the HTTP version used in the request.
References:
Response class for Variant Also Negotiates responses (status code 506).
Transparent content negotiation for the request results in a circular reference.
References:
Raised when trying to activate a gem, and the gem exists on the system, but not the requested version. Instead of rescuing from this class, make sure to rescue from the superclass Gem::LoadError to catch all types of load errors.
Raised when there are conflicting gem specs loaded
Raised when a gem dependencies file specifies a ruby version that does not match the current version.
The Version class processes string versions into comparable values. A version string should normally be a series of numbers separated by periods. Each part (digits separated by periods) is considered its own number, and these are used for sorting. So for instance, 3.10 sorts higher than 3.2 because ten is greater than two.
If any part contains letters (currently only a-z are supported) then that version is considered prerelease. Versions with a prerelease part in the Nth part sort less than versions with N-1 parts. Prerelease parts are sorted alphabetically using the normal Ruby string sorting rules. If a prerelease part contains both letters and numbers, it will be broken into multiple parts to provide expected sort behavior (1.0.a10 becomes 1.0.a.10, and is greater than 1.0.a9).
Prereleases sort between real releases (newest to oldest):
1.0
1.0.b1
1.0.a.2
0.9
If you want to specify a version restriction that includes both prereleases and regular releases of the 1.x series this is the best way:
s.add_dependency 'example', '>= 1.0.0.a', '< 2.0.0'
Users expect to be able to specify a version constraint that gives them some reasonable expectation that new versions of a library will work with their software if the version constraint is true, and not work with their software if the version constraint is false. In other words, the perfect system will accept all compatible versions of the library and reject all incompatible versions.
Libraries change in 3 ways (well, more than 3, but stay focused here!).
The change may be an implementation detail only and have no effect on the client software.
The change may add new features, but do so in a way that client software written to an earlier version is still compatible.
The change may change the public interface of the library in such a way that old software is no longer compatible.
Some examples are appropriate at this point. Suppose I have a Stack class that supports a push and a pop method.
Switch from an array based implementation to a linked-list based implementation.
Provide an automatic (and transparent) backing store for large stacks.
Add a depth method to return the current depth of the stack.
Add a top method that returns the current top of stack (without changing the stack).
Change push so that it returns the item pushed (previously it had no usable return value).
Changes pop so that it no longer returns a value (you must use top to get the top of the stack).
Rename the methods to push_item and pop_item.
Rational Versioning Versions shall be represented by three non-negative integers, separated by periods (e.g. 3.1.4). The first integers is the “major” version number, the second integer is the “minor” version number, and the third integer is the “build” number.
A category 1 change (implementation detail) will increment the build number.
A category 2 change (backwards compatible) will increment the minor version number and reset the build number.
A category 3 change (incompatible) will increment the major build number and reset the minor and build numbers.
Any “public” release of a gem should have a different version. Normally that means incrementing the build number. This means a developer can generate builds all day long, but as soon as they make a public release, the version must be updated.
Let’s work through a project lifecycle using our Stack example from above.
Version 0.0.1
The initial Stack class is release.
Version 0.0.2
Switched to a linked=list implementation because it is cooler.
Version 0.1.0
Added a depth method.
Version 1.0.0
Added top and made pop return nil (pop used to return the old top item).
Version 1.1.0
push now returns the value pushed (it used it return nil).
Version 1.1.1
Fixed a bug in the linked list implementation.
Version 1.1.2
Fixed a bug introduced in the last fix.
Client A needs a stack with basic push/pop capability. They write to the original interface (no top), so their version constraint looks like:
gem 'stack', '>= 0.0'
Essentially, any version is OK with Client A. An incompatible change to the library will cause them grief, but they are willing to take the chance (we call Client A optimistic).
Client B is just like Client A except for two things: (1) They use the depth method and (2) they are worried about future incompatibilities, so they write their version constraint like this:
gem 'stack', '~> 0.1'
The depth method was introduced in version 0.1.0, so that version or anything later is fine, as long as the version stays below version 1.0 where incompatibilities are introduced. We call Client B pessimistic because they are worried about incompatible future changes (it is OK to be pessimistic!).
Version Catastrophe: From: www.zenspider.com/ruby/2008/10/rubygems-how-to-preventing-catastrophe.html
Let’s say you’re depending on the fnord gem version 2.y.z. If you specify your dependency as “>= 2.0.0” then, you’re good, right? What happens if fnord 3.0 comes out and it isn’t backwards compatible with 2.y.z? Your stuff will break as a result of using “>=”. The better route is to specify your dependency with an “approximate” version specifier (“~>”). They’re a tad confusing, so here is how the dependency specifiers work:
Specification From ... To (exclusive) ">= 3.0" 3.0 ... ∞ "~> 3.0" 3.0 ... 4.0 "~> 3.0.0" 3.0.0 ... 3.1 "~> 3.5" 3.5 ... 4.0 "~> 3.5.0" 3.5.0 ... 3.6 "~> 3" 3.0 ... 4.0
For the last example, single-digit versions are automatically extended with a zero to give a sensible result.
Raised by transcoding methods when a named encoding does not correspond with a known converter.
Mixin module that provides the following:
Access to the CGI environment variables as methods. See documentation to the CGI class for a list of these variables. The methods are exposed by removing the leading HTTP_ (if it exists) and downcasing the name. For example, auth_type will return the environment variable AUTH_TYPE, and accept will return the value for HTTP_ACCEPT.
Access to cookies, including the cookies attribute.
Access to parameters, including the params attribute, and overloading [] to perform parameter value lookup by key.
The initialize_query method, for initializing the above mechanisms, handling multipart forms, and allowing the class to be used in “offline” mode.
Utility methods for using the RubyGems API.
The WebauthnListener class retrieves an OTP after a user successfully WebAuthns with the Gem host. An instance opens a socket using the TCPServer instance given and listens for a request from the Gem host. The request should be a GET request to the root path and contains the OTP code in the form of a query parameter ‘code`. The listener will return the code which will be used as the OTP for API requests.
Types of responses sent by the listener after receiving a request:
- 200 OK: OTP code was successfully retrieved - 204 No Content: If the request was an OPTIONS request - 400 Bad Request: If the request did not contain a query parameter `code` - 404 Not Found: The request was not to the root path - 405 Method Not Allowed: OTP code was not retrieved because the request was not a GET/OPTIONS request
Example usage:
thread = Gem::WebauthnListener.listener_thread("https://rubygems.example", server) thread.join otp = thread[:otp] error = thread[:error]
The WebauthnListener Response class is used by the WebauthnListener to create responses to be sent to the Gem host. It creates a Gem::Net::HTTPResponse instance when initialized and can be converted to the appropriate format to be sent by a socket using ‘to_s`. Gem::Net::HTTPResponse instances cannot be directly sent over a socket.
Types of response classes:
- OkResponse - NoContentResponse - BadRequestResponse - NotFoundResponse - MethodNotAllowedResponse
Example usage:
server = TCPServer.new(0) socket = server.accept response = OkResponse.for("https://rubygems.example") socket.print response.to_s socket.close
The WebauthnPoller class retrieves an OTP after a user successfully WebAuthns. An instance polls the Gem host for the OTP code. The polling request (api/v1/webauthn_verification/<webauthn_token>/status.json) is sent to the Gem host every 5 seconds and will timeout after 5 minutes. If the status field in the json response is “success”, the code field will contain the OTP code.
Example usage:
thread = Gem::WebauthnPoller.poll_thread( {}, "RubyGems.org", "https://rubygems.org/api/v1/webauthn_verification/odow34b93t6aPCdY", { email: "email@example.com", password: "password" } ) thread.join otp = thread[:otp] error = thread[:error]
Object is the default root of all Ruby objects. Object inherits from BasicObject which allows creating alternate object hierarchies. Methods on Object are available to all classes unless explicitly overridden.
Object mixes in the Kernel module, making the built-in kernel functions globally accessible. Although the instance methods of Object are defined by the Kernel module, we have chosen to document them here for clarity.
When referencing constants in classes inheriting from Object you do not need to use the full namespace. For example, referencing File inside YourClass will find the top-level File class.
In the descriptions of Object’s methods, the parameter symbol refers to a symbol, which is either a quoted string or a Symbol (such as :name).
First, what’s elsewhere. Class Object:
Inherits from class BasicObject.
Includes module Kernel.
Here, class Object provides methods for:
!~: Returns true if self does not match the given object, otherwise false.
<=>: Returns 0 if self and the given object object are the same object, or if self == object; otherwise returns nil.
===: Implements case equality, effectively the same as calling ==.
eql?: Implements hash equality, effectively the same as calling ==.
kind_of? (aliased as is_a?): Returns whether given argument is an ancestor of the singleton class of self.
instance_of?: Returns whether self is an instance of the given class.
instance_variable_defined?: Returns whether the given instance variable is defined in self.
method: Returns the Method object for the given method in self.
methods: Returns an array of symbol names of public and protected methods in self.
nil?: Returns false. (Only nil responds true to method nil?.)
object_id: Returns an integer corresponding to self that is unique for the current process
private_methods: Returns an array of the symbol names of the private methods in self.
protected_methods: Returns an array of the symbol names of the protected methods in self.
public_method: Returns the Method object for the given public method in self.
public_methods: Returns an array of the symbol names of the public methods in self.
respond_to?: Returns whether self responds to the given method.
singleton_class: Returns the singleton class of self.
singleton_method: Returns the Method object for the given singleton method in self.
singleton_methods: Returns an array of the symbol names of the singleton methods in self.
define_singleton_method: Defines a singleton method in self for the given symbol method-name and block or proc.
extend: Includes the given modules in the singleton class of self.
public_send: Calls the given public method in self with the given argument.
send: Calls the given method in self with the given argument.
instance_variable_get: Returns the value of the given instance variable in self, or nil if the instance variable is not set.
instance_variable_set: Sets the value of the given instance variable in self to the given object.
instance_variables: Returns an array of the symbol names of the instance variables in self.
remove_instance_variable: Removes the named instance variable from self.
clone: Returns a shallow copy of self, including singleton class and frozen state.
define_singleton_method: Defines a singleton method in self for the given symbol method-name and block or proc.
dup: Returns a shallow unfrozen copy of self.
enum_for (aliased as to_enum): Returns an Enumerator for self using the using the given method, arguments, and block.
extend: Includes the given modules in the singleton class of self.
freeze: Prevents further modifications to self.
hash: Returns the integer hash value for self.
inspect: Returns a human-readable string representation of self.
itself: Returns self.
method_missing: Method called when an undefined method is called on self.
public_send: Calls the given public method in self with the given argument.
send: Calls the given method in self with the given argument.
to_s: Returns a string representation of self.
DateTime A subclass of Date that easily handles date, hour, minute, second, and offset.
DateTime class is considered deprecated. Use Time class.
DateTime does not consider any leap seconds, does not track any summer time rules.
A DateTime object is created with DateTime::new, DateTime::jd, DateTime::ordinal, DateTime::commercial, DateTime::parse, DateTime::strptime, DateTime::now, Time#to_datetime, etc.
require 'date' DateTime.new(2001,2,3,4,5,6) #=> #<DateTime: 2001-02-03T04:05:06+00:00 ...>
The last element of day, hour, minute, or second can be a fractional number. The fractional number’s precision is assumed at most nanosecond.
DateTime.new(2001,2,3.5) #=> #<DateTime: 2001-02-03T12:00:00+00:00 ...>
An optional argument, the offset, indicates the difference between the local time and UTC. For example, Rational(3,24) represents ahead of 3 hours of UTC, Rational(-5,24) represents behind of 5 hours of UTC. The offset should be -1 to +1, and its precision is assumed at most second. The default value is zero (equals to UTC).
DateTime.new(2001,2,3,4,5,6,Rational(3,24)) #=> #<DateTime: 2001-02-03T04:05:06+03:00 ...>
The offset also accepts string form:
DateTime.new(2001,2,3,4,5,6,'+03:00') #=> #<DateTime: 2001-02-03T04:05:06+03:00 ...>
An optional argument, the day of calendar reform (start), denotes a Julian day number, which should be 2298874 to 2426355 or negative/positive infinity. The default value is Date::ITALY (2299161=1582-10-15).
A DateTime object has various methods. See each reference.
d = DateTime.parse('3rd Feb 2001 04:05:06+03:30') #=> #<DateTime: 2001-02-03T04:05:06+03:30 ...> d.hour #=> 4 d.min #=> 5 d.sec #=> 6 d.offset #=> (7/48) d.zone #=> "+03:30" d += Rational('1.5') #=> #<DateTime: 2001-02-04%16:05:06+03:30 ...> d = d.new_offset('+09:00') #=> #<DateTime: 2001-02-04%21:35:06+09:00 ...> d.strftime('%I:%M:%S %p') #=> "09:35:06 PM" d > DateTime.new(1999) #=> true
DateTime and when should you use Time? It’s a common misconception that William Shakespeare and Miguel de Cervantes died on the same day in history - so much so that UNESCO named April 23 as World Book Day because of this fact. However, because England hadn’t yet adopted the Gregorian Calendar Reform (and wouldn’t until 1752) their deaths are actually 10 days apart. Since Ruby’s Time class implements a proleptic Gregorian calendar and has no concept of calendar reform there’s no way to express this with Time objects. This is where DateTime steps in:
shakespeare = DateTime.iso8601('1616-04-23', Date::ENGLAND) #=> Tue, 23 Apr 1616 00:00:00 +0000 cervantes = DateTime.iso8601('1616-04-23', Date::ITALY) #=> Sat, 23 Apr 1616 00:00:00 +0000
Already you can see something is weird - the days of the week are different. Taking this further:
cervantes == shakespeare #=> false (shakespeare - cervantes).to_i #=> 10
This shows that in fact they died 10 days apart (in reality 11 days since Cervantes died a day earlier but was buried on the 23rd). We can see the actual date of Shakespeare’s death by using the gregorian method to convert it:
shakespeare.gregorian #=> Tue, 03 May 1616 00:00:00 +0000
So there’s an argument that all the celebrations that take place on the 23rd April in Stratford-upon-Avon are actually the wrong date since England is now using the Gregorian calendar. You can see why when we transition across the reform date boundary:
# start off with the anniversary of Shakespeare's birth in 1751 shakespeare = DateTime.iso8601('1751-04-23', Date::ENGLAND) #=> Tue, 23 Apr 1751 00:00:00 +0000 # add 366 days since 1752 is a leap year and April 23 is after February 29 shakespeare + 366 #=> Thu, 23 Apr 1752 00:00:00 +0000 # add another 365 days to take us to the anniversary in 1753 shakespeare + 366 + 365 #=> Fri, 04 May 1753 00:00:00 +0000
As you can see, if we’re accurately tracking the number of solar years since Shakespeare’s birthday then the correct anniversary date would be the 4th May and not the 23rd April.
So when should you use DateTime in Ruby and when should you use Time? Almost certainly you’ll want to use Time since your app is probably dealing with current dates and times. However, if you need to deal with dates and times in a historical context you’ll want to use DateTime to avoid making the same mistakes as UNESCO. If you also have to deal with timezones then best of luck - just bear in mind that you’ll probably be dealing with local solar times, since it wasn’t until the 19th century that the introduction of the railways necessitated the need for Standard Time and eventually timezones.
A Time object represents a date and time:
Time.new(2000, 1, 1, 0, 0, 0) # => 2000-01-01 00:00:00 -0600
Although its value can be expressed as a single numeric (see Epoch Seconds below), it can be convenient to deal with the value by parts:
t = Time.new(-2000, 1, 1, 0, 0, 0.0) # => -2000-01-01 00:00:00 -0600 t.year # => -2000 t.month # => 1 t.mday # => 1 t.hour # => 0 t.min # => 0 t.sec # => 0 t.subsec # => 0 t = Time.new(2000, 12, 31, 23, 59, 59.5) # => 2000-12-31 23:59:59.5 -0600 t.year # => 2000 t.month # => 12 t.mday # => 31 t.hour # => 23 t.min # => 59 t.sec # => 59 t.subsec # => (1/2)
Epoch seconds is the exact number of seconds (including fractional subseconds) since the Unix Epoch, January 1, 1970.
You can retrieve that value exactly using method Time.to_r:
Time.at(0).to_r # => (0/1) Time.at(0.999999).to_r # => (9007190247541737/9007199254740992)
Other retrieval methods such as Time#to_i and Time#to_f may return a value that rounds or truncates subseconds.
A Time object derived from the system clock (for example, by method Time.now) has the resolution supported by the system.
Time implementation uses a signed 63 bit integer, Integer(T_BIGNUM), or Rational. It is a number of nanoseconds since the Epoch. The signed 63 bit integer can represent 1823-11-12 to 2116-02-20. When Integer or Rational is used (before 1823, after 2116, under nanosecond), Time works slower than when the signed 63 bit integer is used.
Ruby uses the C function “localtime” and “gmtime” to map between the number and 6-tuple (year,month,day,hour,minute,second). “localtime” is used for local time and “gmtime” is used for UTC.
Integer(T_BIGNUM) and Rational has no range limit, but the localtime and gmtime has range limits due to the C types “time_t” and “struct tm”. If that limit is exceeded, Ruby extrapolates the localtime function.
The Time class always uses the Gregorian calendar. I.e. the proleptic Gregorian calendar is used. Other calendars, such as Julian calendar, are not supported.
“time_t” can represent 1901-12-14 to 2038-01-19 if it is 32 bit signed integer, -292277022657-01-27 to 292277026596-12-05 if it is 64 bit signed integer. However “localtime” on some platforms doesn’t supports negative time_t (before 1970).
“struct tm” has tm_year member to represent years. (tm_year = 0 means the year 1900.) It is defined as int in the C standard. tm_year can represent between -2147481748 to 2147485547 if int is 32 bit.
Ruby supports leap seconds as far as if the C function “localtime” and “gmtime” supports it. They use the tz database in most Unix systems. The tz database has timezones which supports leap seconds. For example, “Asia/Tokyo” doesn’t support leap seconds but “right/Asia/Tokyo” supports leap seconds. So, Ruby supports leap seconds if the TZ environment variable is set to “right/Asia/Tokyo” in most Unix systems.
All of these examples were done using the EST timezone which is GMT-5.
Time Instance You can create a new instance of Time with Time.new. This will use the current system time. Time.now is an alias for this. You can also pass parts of the time to Time.new such as year, month, minute, etc. When you want to construct a time this way you must pass at least a year. If you pass the year with nothing else time will default to January 1 of that year at 00:00:00 with the current system timezone. Here are some examples:
Time.new(2002) #=> 2002-01-01 00:00:00 -0500 Time.new(2002, 10) #=> 2002-10-01 00:00:00 -0500 Time.new(2002, 10, 31) #=> 2002-10-31 00:00:00 -0500
You can pass a UTC offset:
Time.new(2002, 10, 31, 2, 2, 2, "+02:00") #=> 2002-10-31 02:02:02 +0200
zone = timezone("Europe/Athens") # Eastern European Time, UTC+2 Time.new(2002, 10, 31, 2, 2, 2, zone) #=> 2002-10-31 02:02:02 +0200
You can also use Time.local and Time.utc to infer local and UTC timezones instead of using the current system setting.
You can also create a new time using Time.at which takes the number of seconds (with subsecond) since the Unix Epoch.
Time.at(628232400) #=> 1989-11-28 00:00:00 -0500
Time Once you have an instance of Time there is a multitude of things you can do with it. Below are some examples. For all of the following examples, we will work on the assumption that you have done the following:
t = Time.new(1993, 02, 24, 12, 0, 0, "+09:00")
Was that a monday?
t.monday? #=> false
What year was that again?
t.year #=> 1993
Was it daylight savings at the time?
t.dst? #=> false
What’s the day a year later?
t + (60*60*24*365) #=> 1994-02-24 12:00:00 +0900
How many seconds was that since the Unix Epoch?
t.to_i #=> 730522800
You can also do standard functions like compare two times.
t1 = Time.new(2010) t2 = Time.new(2011) t1 == t2 #=> false t1 == t1 #=> true t1 < t2 #=> true t1 > t2 #=> false Time.new(2010,10,31).between?(t1, t2) #=> true
First, what’s elsewhere. Class Time:
Inherits from class Object.
Includes module Comparable.
Here, class Time provides methods that are useful for:
{Creating Time objects}[rdoc-ref:Time@Methods+for+Creating].
{Fetching Time values}[rdoc-ref:Time@Methods+for+Fetching].
{Querying a Time object}[rdoc-ref:Time@Methods+for+Querying].
{Comparing Time objects}[rdoc-ref:Time@Methods+for+Comparing].
{Converting a Time object}[rdoc-ref:Time@Methods+for+Converting].
{Rounding a Time}.
::new: Returns a new time from specified arguments (year, month, etc.), including an optional timezone value.
::local (aliased as ::mktime): Same as ::new, except the timezone is the local timezone.
::utc (aliased as ::gm): Same as ::new, except the timezone is UTC.
::at: Returns a new time based on seconds since epoch.
::now: Returns a new time based on the current system time.
+ (plus): Returns a new time increased by the given number of seconds.
- (minus): Returns a new time decreased by the given number of seconds.
year: Returns the year of the time.
hour: Returns the hours value for the time.
min: Returns the minutes value for the time.
sec: Returns the seconds value for the time.
usec (aliased as tv_usec): Returns the number of microseconds in the subseconds value of the time.
nsec (aliased as tv_nsec: Returns the number of nanoseconds in the subsecond part of the time.
subsec: Returns the subseconds value for the time.
wday: Returns the integer weekday value of the time (0 == Sunday).
yday: Returns the integer yearday value of the time (1 == January 1).
hash: Returns the integer hash value for the time.
utc_offset (aliased as gmt_offset and gmtoff): Returns the offset in seconds between time and UTC.
to_f: Returns the float number of seconds since epoch for the time.
to_i (aliased as tv_sec): Returns the integer number of seconds since epoch for the time.
to_r: Returns the Rational number of seconds since epoch for the time.
zone: Returns a string representation of the timezone of the time.
dst? (aliased as isdst): Returns whether the time is DST (daylight saving time).
sunday?: Returns whether the time is a Sunday.
monday?: Returns whether the time is a Monday.
tuesday?: Returns whether the time is a Tuesday.
wednesday?: Returns whether the time is a Wednesday.
thursday?: Returns whether the time is a Thursday.
friday?: Returns whether time is a Friday.
saturday?: Returns whether the time is a Saturday.
inspect: Returns the time in detail as a string.
strftime: Returns the time as a string, according to a given format.
to_a: Returns a 10-element array of values from the time.
to_s: Returns a string representation of the time.
getutc (aliased as getgm): Returns a new time converted to UTC.
getlocal: Returns a new time converted to local time.
localtime: Converts time to local time in place.
deconstruct_keys: Returns a hash of time components used in pattern-matching.
round:Returns a new time with subseconds rounded.
ceil: Returns a new time with subseconds raised to a ceiling.
floor: Returns a new time with subseconds lowered to a floor.
For the forms of argument zone, see Timezone Specifiers.
Certain Time methods accept arguments that specify timezones:
Time.at: keyword argument in:.
Time.new: positional argument zone or keyword argument in:.
Time.now: keyword argument in:.
Time#getlocal: positional argument zone.
Time#localtime: positional argument zone.
The value given with any of these must be one of the following (each detailed below):
The zone value may be a string offset from UTC in the form '+HH:MM' or '-HH:MM', where:
HH is the 2-digit hour in the range 0..23.
MM is the 2-digit minute in the range 0..59.
Examples:
t = Time.utc(2000, 1, 1, 20, 15, 1) # => 2000-01-01 20:15:01 UTC Time.at(t, in: '-23:59') # => 1999-12-31 20:16:01 -2359 Time.at(t, in: '+23:59') # => 2000-01-02 20:14:01 +2359
The zone value may be a letter in the range 'A'..'I' or 'K'..'Z'; see List of military time zones:
t = Time.utc(2000, 1, 1, 20, 15, 1) # => 2000-01-01 20:15:01 UTC Time.at(t, in: 'A') # => 2000-01-01 21:15:01 +0100 Time.at(t, in: 'I') # => 2000-01-02 05:15:01 +0900 Time.at(t, in: 'K') # => 2000-01-02 06:15:01 +1000 Time.at(t, in: 'Y') # => 2000-01-01 08:15:01 -1200 Time.at(t, in: 'Z') # => 2000-01-01 20:15:01 UTC
The zone value may be an integer number of seconds in the range -86399..86399:
t = Time.utc(2000, 1, 1, 20, 15, 1) # => 2000-01-01 20:15:01 UTC Time.at(t, in: -86399) # => 1999-12-31 20:15:02 -235959 Time.at(t, in: 86399) # => 2000-01-02 20:15:00 +235959
The zone value may be an object responding to certain timezone methods, an instance of Timezone and TZInfo for example.
The timezone methods are:
local_to_utc:
Called when Time.new is invoked with tz as the value of positional argument zone or keyword argument in:.
Argument: a Time-like object.
Returns: a Time-like object in the UTC timezone.
utc_to_local:
Called when Time.at or Time.now is invoked with tz as the value for keyword argument in:, and when Time#getlocal or Time#localtime is called with tz as the value for positional argument zone.
Argument: a Time-like object.
Returns: a Time-like object in the local timezone.
A custom timezone class may have these instance methods, which will be called if defined:
abbr:
Called when Time#strftime is invoked with a format involving %Z.
Argument: a Time-like object.
Returns: a string abbreviation for the timezone name.
dst?:
Called when Time.at or Time.now is invoked with tz as the value for keyword argument in:, and when Time#getlocal or Time#localtime is called with tz as the value for positional argument zone.
Argument: a Time-like object.
Returns: whether the time is daylight saving time.
name:
Called when Marshal.dump(t) is invoked
Argument: none.
Returns: the string name of the timezone.
Time-Like Objects A Time-like object is a container object capable of interfacing with timezone libraries for timezone conversion.
The argument to the timezone conversion methods above will have attributes similar to Time, except that timezone related attributes are meaningless.
The objects returned by local_to_utc and utc_to_local methods of the timezone object may be of the same class as their arguments, of arbitrary object classes, or of class Integer.
For a returned class other than Integer, the class must have the following methods:
year
mon
mday
hour
min
sec
isdst
to_i
For a returned Integer, its components, decomposed in UTC, are interpreted as times in the specified timezone.
If the class (the receiver of class methods, or the class of the receiver of instance methods) has find_timezone singleton method, this method is called to achieve the corresponding timezone object from a timezone name.
For example, using Timezone:
class TimeWithTimezone < Time require 'timezone' def self.find_timezone(z) = Timezone[z] end TimeWithTimezone.now(in: "America/New_York") #=> 2023-12-25 00:00:00 -0500 TimeWithTimezone.new("2023-12-25 America/New_York") #=> 2023-12-25 00:00:00 -0500
Or, using TZInfo:
class TimeWithTZInfo < Time require 'tzinfo' def self.find_timezone(z) = TZInfo::Timezone.get(z) end TimeWithTZInfo.now(in: "America/New_York") #=> 2023-12-25 00:00:00 -0500 TimeWithTZInfo.new("2023-12-25 America/New_York") #=> 2023-12-25 00:00:00 -0500
You can define this method per subclasses, or on the toplevel Time class.
An instance of class IO (commonly called a stream) represents an input/output stream in the underlying operating system. Class IO is the basis for input and output in Ruby.
Class File is the only class in the Ruby core that is a subclass of IO. Some classes in the Ruby standard library are also subclasses of IO; these include TCPSocket and UDPSocket.
The global constant ARGF (also accessible as $<) provides an IO-like stream that allows access to all file paths found in ARGV (or found in STDIN if ARGV is empty). ARGF is not itself a subclass of IO.
Class StringIO provides an IO-like stream that handles a String. StringIO is not itself a subclass of IO.
Important objects based on IO include:
$stdin.
$stdout.
$stderr.
Instances of class File.
An instance of IO may be created using:
IO.new: returns a new IO object for the given integer file descriptor.
IO.open: passes a new IO object to the given block.
IO.popen: returns a new IO object that is connected to the $stdin and $stdout of a newly-launched subprocess.
Kernel#open: Returns a new IO object connected to a given source: stream, file, or subprocess.
Like a File stream, an IO stream has:
A read/write mode, which may be read-only, write-only, or read/write; see Read/Write Mode.
A data mode, which may be text-only or binary; see Data Mode.
Internal and external encodings; see Encodings.
And like other IO streams, it has:
A position, which determines where in the stream the next read or write is to occur; see Position.
A line number, which is a special, line-oriented, “position” (different from the position mentioned above); see Line Number.
io/console Extension io/console provides numerous methods for interacting with the console; requiring it adds numerous methods to class IO.
Many examples here use these variables:
# English text with newlines. text = <<~EOT First line Second line Fourth line Fifth line EOT # Russian text. russian = "\u{442 435 441 442}" # => "тест" # Binary data. data = "\u9990\u9991\u9992\u9993\u9994" # Text file. File.write('t.txt', text) # File with Russian text. File.write('t.rus', russian) # File with binary data. f = File.new('t.dat', 'wb:UTF-16') f.write(data) f.close
A number of IO methods accept optional keyword arguments that determine how a new stream is to be opened:
:mode: Stream mode.
:flags: Integer file open flags; If mode is also given, the two are bitwise-ORed.
:external_encoding: External encoding for the stream.
:internal_encoding: Internal encoding for the stream. '-' is a synonym for the default internal encoding. If the value is nil no conversion occurs.
:encoding: Specifies external and internal encodings as 'extern:intern'.
:textmode: If a truthy value, specifies the mode as text-only, binary otherwise.
:binmode: If a truthy value, specifies the mode as binary, text-only otherwise.
:autoclose: If a truthy value, specifies that the fd will close when the stream closes; otherwise it remains open.
:path: If a string value is provided, it is used in inspect and is available as path method.
Also available are the options offered in String#encode, which may control conversion between external and internal encoding.
You can perform basic stream IO with these methods, which typically operate on multi-byte strings:
IO#read: Reads and returns some or all of the remaining bytes from the stream.
IO#write: Writes zero or more strings to the stream; each given object that is not already a string is converted via to_s.
An IO stream has a nonnegative integer position, which is the byte offset at which the next read or write is to occur. A new stream has position zero (and line number zero); method rewind resets the position (and line number) to zero.
The relevant methods:
IO#tell (aliased as #pos): Returns the current position (in bytes) in the stream.
IO#pos=: Sets the position of the stream to a given integer new_position (in bytes).
IO#seek: Sets the position of the stream to a given integer offset (in bytes), relative to a given position whence (indicating the beginning, end, or current position).
IO#rewind: Positions the stream at the beginning (also resetting the line number).
A new IO stream may be open for reading, open for writing, or both.
A stream is automatically closed when claimed by the garbage collector.
Attempted reading or writing on a closed stream raises an exception.
The relevant methods:
IO#close: Closes the stream for both reading and writing.
IO#close_read: Closes the stream for reading.
IO#close_write: Closes the stream for writing.
IO#closed?: Returns whether the stream is closed.
You can query whether a stream is positioned at its end:
IO#eof? (also aliased as #eof): Returns whether the stream is at end-of-stream.
You can reposition to end-of-stream by using method IO#seek:
f = File.new('t.txt') f.eof? # => false f.seek(0, :END) f.eof? # => true f.close
Or by reading all stream content (which is slower than using IO#seek):
f.rewind f.eof? # => false f.read # => "First line\nSecond line\n\nFourth line\nFifth line\n" f.eof? # => true
Class IO supports line-oriented input and output
Class IO supports line-oriented input for files and IO streams
You can read lines from a file using these methods:
IO.foreach: Reads each line and passes it to the given block.
IO.readlines: Reads and returns all lines in an array.
For each of these methods:
You can specify open options.
Line parsing depends on the effective line separator; see Line Separator.
The length of each returned line depends on the effective line limit; see Line Limit.
You can read lines from an IO stream using these methods:
IO#each_line: Reads each remaining line, passing it to the given block.
IO#gets: Returns the next line.
IO#readline: Like gets, but raises an exception at end-of-stream.
IO#readlines: Returns all remaining lines in an array.
For each of these methods:
Reading may begin mid-line, depending on the stream’s position; see Position.
Line parsing depends on the effective line separator; see Line Separator.
The length of each returned line depends on the effective line limit; see Line Limit.
Each of the line input methods uses a line separator: the string that determines what is considered a line; it is sometimes called the input record separator.
The default line separator is taken from global variable $/, whose initial value is "\n".
Generally, the line to be read next is all data from the current position to the next line separator (but see Special Line Separator Values):
f = File.new('t.txt') # Method gets with no sep argument returns the next line, according to $/. f.gets # => "First line\n" f.gets # => "Second line\n" f.gets # => "\n" f.gets # => "Fourth line\n" f.gets # => "Fifth line\n" f.close
You can use a different line separator by passing argument sep:
f = File.new('t.txt') f.gets('l') # => "First l" f.gets('li') # => "ine\nSecond li" f.gets('lin') # => "ne\n\nFourth lin" f.gets # => "e\n" f.close
Or by setting global variable $/:
f = File.new('t.txt') $/ = 'l' f.gets # => "First l" f.gets # => "ine\nSecond l" f.gets # => "ine\n\nFourth l" f.close
Each of the line input methods accepts two special values for parameter sep:
nil: The entire stream is to be read (“slurped”) into a single string:
f = File.new('t.txt') f.gets(nil) # => "First line\nSecond line\n\nFourth line\nFifth line\n" f.close
'' (the empty string): The next “paragraph” is to be read (paragraphs being separated by two consecutive line separators):
f = File.new('t.txt') f.gets('') # => "First line\nSecond line\n\n" f.gets('') # => "Fourth line\nFifth line\n" f.close
Each of the line input methods uses an integer line limit, which restricts the number of bytes that may be returned. (A multi-byte character will not be split, and so a returned line may be slightly longer than the limit).
The default limit value is -1; any negative limit value means that there is no limit.
If there is no limit, the line is determined only by sep.
# Text with 1-byte characters. File.open('t.txt') {|f| f.gets(1) } # => "F" File.open('t.txt') {|f| f.gets(2) } # => "Fi" File.open('t.txt') {|f| f.gets(3) } # => "Fir" File.open('t.txt') {|f| f.gets(4) } # => "Firs" # No more than one line. File.open('t.txt') {|f| f.gets(10) } # => "First line" File.open('t.txt') {|f| f.gets(11) } # => "First line\n" File.open('t.txt') {|f| f.gets(12) } # => "First line\n" # Text with 2-byte characters, which will not be split. File.open('t.rus') {|f| f.gets(1).size } # => 1 File.open('t.rus') {|f| f.gets(2).size } # => 1 File.open('t.rus') {|f| f.gets(3).size } # => 2 File.open('t.rus') {|f| f.gets(4).size } # => 2
With arguments sep and limit given, combines the two behaviors:
Returns the next line as determined by line separator sep.
But returns no more bytes than are allowed by the limit limit.
Example:
File.open('t.txt') {|f| f.gets('li', 20) } # => "First li" File.open('t.txt') {|f| f.gets('li', 2) } # => "Fi"
A readable IO stream has a non-negative integer line number:
IO#lineno: Returns the line number.
IO#lineno=: Resets and returns the line number.
Unless modified by a call to method IO#lineno=, the line number is the number of lines read by certain line-oriented methods, according to the effective line separator:
IO.foreach: Increments the line number on each call to the block.
IO#each_line: Increments the line number on each call to the block.
IO#gets: Increments the line number.
IO#readline: Increments the line number.
IO#readlines: Increments the line number for each line read.
A new stream is initially has line number zero (and position zero); method rewind resets the line number (and position) to zero:
f = File.new('t.txt') f.lineno # => 0 f.gets # => "First line\n" f.lineno # => 1 f.rewind f.lineno # => 0 f.close
Reading lines from a stream usually changes its line number:
f = File.new('t.txt', 'r') f.lineno # => 0 f.readline # => "This is line one.\n" f.lineno # => 1 f.readline # => "This is the second line.\n" f.lineno # => 2 f.readline # => "Here's the third line.\n" f.lineno # => 3 f.eof? # => true f.close
Iterating over lines in a stream usually changes its line number:
File.open('t.txt') do |f| f.each_line do |line| p "position=#{f.pos} eof?=#{f.eof?} lineno=#{f.lineno}" end end
Output:
"position=11 eof?=false lineno=1" "position=23 eof?=false lineno=2" "position=24 eof?=false lineno=3" "position=36 eof?=false lineno=4" "position=47 eof?=true lineno=5"
Unlike the stream’s position, the line number does not affect where the next read or write will occur:
f = File.new('t.txt') f.lineno = 1000 f.lineno # => 1000 f.gets # => "First line\n" f.lineno # => 1001 f.close
Associated with the line number is the global variable $.:
When a stream is opened, $. is not set; its value is left over from previous activity in the process:
$. = 41 f = File.new('t.txt') $. = 41 # => 41 f.close
When a stream is read, $. is set to the line number for that stream:
f0 = File.new('t.txt') f1 = File.new('t.dat') f0.readlines # => ["First line\n", "Second line\n", "\n", "Fourth line\n", "Fifth line\n"] $. # => 5 f1.readlines # => ["\xFE\xFF\x99\x90\x99\x91\x99\x92\x99\x93\x99\x94"] $. # => 1 f0.close f1.close
Methods IO#rewind and IO#seek do not affect $.:
f = File.new('t.txt') f.readlines # => ["First line\n", "Second line\n", "\n", "Fourth line\n", "Fifth line\n"] $. # => 5 f.rewind f.seek(0, :SET) $. # => 5 f.close
You can write to an IO stream line-by-line using this method:
IO#puts: Writes objects to the stream.
You can process an IO stream character-by-character using these methods:
IO#getc: Reads and returns the next character from the stream.
IO#readchar: Like getc, but raises an exception at end-of-stream.
IO#ungetc: Pushes back (“unshifts”) a character or integer onto the stream.
IO#putc: Writes a character to the stream.
IO#each_char: Reads each remaining character in the stream, passing the character to the given block.
You can process an IO stream byte-by-byte using these methods:
IO#getbyte: Returns the next 8-bit byte as an integer in range 0..255.
IO#readbyte: Like getbyte, but raises an exception if at end-of-stream.
IO#ungetbyte: Pushes back (“unshifts”) a byte back onto the stream.
IO#each_byte: Reads each remaining byte in the stream, passing the byte to the given block.
You can process an IO stream codepoint-by-codepoint:
IO#each_codepoint: Reads each remaining codepoint, passing it to the given block.
First, what’s elsewhere. Class IO:
Inherits from class Object.
Includes module Enumerable, which provides dozens of additional methods.
Here, class IO provides methods that are useful for:
::new (aliased as ::for_fd): Creates and returns a new IO object for the given integer file descriptor.
::open: Creates a new IO object.
::pipe: Creates a connected pair of reader and writer IO objects.
::popen: Creates an IO object to interact with a subprocess.
::select: Selects which given IO instances are ready for reading, writing, or have pending exceptions.
::binread: Returns a binary string with all or a subset of bytes from the given file.
::read: Returns a string with all or a subset of bytes from the given file.
::readlines: Returns an array of strings, which are the lines from the given file.
getbyte: Returns the next 8-bit byte read from self as an integer.
getc: Returns the next character read from self as a string.
gets: Returns the line read from self.
pread: Returns all or the next n bytes read from self, not updating the receiver’s offset.
read: Returns all remaining or the next n bytes read from self for a given n.
read_nonblock: the next n bytes read from self for a given n, in non-block mode.
readbyte: Returns the next byte read from self; same as getbyte, but raises an exception on end-of-stream.
readchar: Returns the next character read from self; same as getc, but raises an exception on end-of-stream.
readline: Returns the next line read from self; same as getline, but raises an exception of end-of-stream.
readlines: Returns an array of all lines read read from self.
readpartial: Returns up to the given number of bytes from self.
::binwrite: Writes the given string to the file at the given filepath, in binary mode.
::write: Writes the given string to self.
<<: Appends the given string to self.
print: Prints last read line or given objects to self.
printf: Writes to self based on the given format string and objects.
putc: Writes a character to self.
puts: Writes lines to self, making sure line ends with a newline.
pwrite: Writes the given string at the given offset, not updating the receiver’s offset.
write: Writes one or more given strings to self.
write_nonblock: Writes one or more given strings to self in non-blocking mode.
lineno: Returns the current line number in self.
lineno=: Sets the line number is self.
pos (aliased as tell): Returns the current byte offset in self.
pos=: Sets the byte offset in self.
reopen: Reassociates self with a new or existing IO stream.
rewind: Positions self to the beginning of input.
seek: Sets the offset for self relative to given position.
::foreach: Yields each line of given file to the block.
each (aliased as each_line): Calls the given block with each successive line in self.
each_byte: Calls the given block with each successive byte in self as an integer.
each_char: Calls the given block with each successive character in self as a string.
each_codepoint: Calls the given block with each successive codepoint in self as an integer.
autoclose=: Sets whether self auto-closes.
binmode: Sets self to binary mode.
close: Closes self.
close_on_exec=: Sets the close-on-exec flag.
close_read: Closes self for reading.
close_write: Closes self for writing.
set_encoding: Sets the encoding for self.
set_encoding_by_bom: Sets the encoding for self, based on its Unicode byte-order-mark.
sync=: Sets the sync-mode to the given value.
autoclose?: Returns whether self auto-closes.
binmode?: Returns whether self is in binary mode.
close_on_exec?: Returns the close-on-exec flag for self.
closed?: Returns whether self is closed.
eof? (aliased as eof): Returns whether self is at end-of-stream.
external_encoding: Returns the external encoding object for self.
fileno (aliased as to_i): Returns the integer file descriptor for self
internal_encoding: Returns the internal encoding object for self.
pid: Returns the process ID of a child process associated with self, if self was created by ::popen.
stat: Returns the File::Stat object containing status information for self.
sync: Returns whether self is in sync-mode.
tty? (aliased as isatty): Returns whether self is a terminal.
fdatasync: Immediately writes all buffered data in self to disk.
flush: Flushes any buffered data within self to the underlying operating system.
fsync: Immediately writes all buffered data and attributes in self to disk.
ungetbyte: Prepends buffer for self with given integer byte or string.
ungetc: Prepends buffer for self with given string.
::sysopen: Opens the file given by its path, returning the integer file descriptor.
advise: Announces the intention to access data from self in a specific way.
fcntl: Passes a low-level command to the file specified by the given file descriptor.
ioctl: Passes a low-level command to the device specified by the given file descriptor.
sysread: Returns up to the next n bytes read from self using a low-level read.
sysseek: Sets the offset for self.
syswrite: Writes the given string to self using a low-level write.
::copy_stream: Copies data from a source to a destination, each of which is a filepath or an IO-like object.
::try_convert: Returns a new IO object resulting from converting the given object.
inspect: Returns the string representation of self.
An OpenStruct is a data structure, similar to a Hash, that allows the definition of arbitrary attributes with their accompanying values. This is accomplished by using Ruby’s metaprogramming to define methods on the class itself.
require "ostruct" person = OpenStruct.new person.name = "John Smith" person.age = 70 person.name # => "John Smith" person.age # => 70 person.address # => nil
An OpenStruct employs a Hash internally to store the attributes and values and can even be initialized with one:
australia = OpenStruct.new(:country => "Australia", :capital => "Canberra") # => #<OpenStruct country="Australia", capital="Canberra">
Hash keys with spaces or characters that could normally not be used for method calls (e.g. ()[]*) will not be immediately available on the OpenStruct object as a method for retrieval or assignment, but can still be reached through the Object#send method or using [].
measurements = OpenStruct.new("length (in inches)" => 24) measurements[:"length (in inches)"] # => 24 measurements.send("length (in inches)") # => 24 message = OpenStruct.new(:queued? => true) message.queued? # => true message.send("queued?=", false) message.queued? # => false
Removing the presence of an attribute requires the execution of the delete_field method as setting the property value to nil will not remove the attribute.
first_pet = OpenStruct.new(:name => "Rowdy", :owner => "John Smith") second_pet = OpenStruct.new(:name => "Rowdy") first_pet.owner = nil first_pet # => #<OpenStruct name="Rowdy", owner=nil> first_pet == second_pet # => false first_pet.delete_field(:owner) first_pet # => #<OpenStruct name="Rowdy"> first_pet == second_pet # => true
Ractor compatibility: A frozen OpenStruct with shareable values is itself shareable.
An OpenStruct utilizes Ruby’s method lookup structure to find and define the necessary methods for properties. This is accomplished through the methods method_missing and define_singleton_method.
This should be a consideration if there is a concern about the performance of the objects that are created, as there is much more overhead in the setting of these properties compared to using a Hash or a Struct. Creating an open struct from a small Hash and accessing a few of the entries can be 200 times slower than accessing the hash directly.
This is a potential security issue; building OpenStruct from untrusted user data (e.g. JSON web request) may be susceptible to a “symbol denial of service” attack since the keys create methods and names of methods are never garbage collected.
This may also be the source of incompatibilities between Ruby versions:
o = OpenStruct.new o.then # => nil in Ruby < 2.6, enumerator for Ruby >= 2.6
Builtin methods may be overwritten this way, which may be a source of bugs or security issues:
o = OpenStruct.new o.methods # => [:to_h, :marshal_load, :marshal_dump, :each_pair, ... o.methods = [:foo, :bar] o.methods # => [:foo, :bar]
To help remedy clashes, OpenStruct uses only protected/private methods ending with ! and defines aliases for builtin public methods by adding a !:
o = OpenStruct.new(make: 'Bentley', class: :luxury) o.class # => :luxury o.class! # => OpenStruct
It is recommended (but not enforced) to not use fields ending in !; Note that a subclass’ methods may not be overwritten, nor can OpenStruct’s own methods ending with !.
For all these reasons, consider not using OpenStruct at all.