Opens the file named by filename according to the given mode and returns a new File object.
See IO.new for a description of mode and opt.
If a file is being created, permission bits may be given in perm. These mode and permission bits are platform dependent; on Unix systems, see open(2) and chmod(2) man pages for details.
The new File object is buffered mode (or non-sync mode), unless filename is a tty. See IO#flush, IO#fsync, IO#fdatasync, and IO#sync= about sync mode.
f = File.new("testfile", "r") f = File.new("newfile", "w+") f = File.new("newfile", File::CREAT|File::TRUNC|File::RDWR, 0644)
Creates a new Enumerator object, which can be used as an Enumerable.
In the first form, iteration is defined by the given block, in which a “yielder” object, given as block parameter, can be used to yield a value by calling the yield method (aliased as <<):
fib = Enumerator.new do |y| a = b = 1 loop do y << a a, b = b, a + b end end fib.take(10) # => [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
The optional parameter can be used to specify how to calculate the size in a lazy fashion (see Enumerator#size). It can either be a value or a callable object.
In the deprecated second form, a generated Enumerator iterates over the given object using the given method with the given arguments passed.
Use of this form is discouraged. Use Object#enum_for or Object#to_enum instead.
e = Enumerator.new(ObjectSpace, :each_object) #-> ObjectSpace.enum_for(:each_object) e.select { |obj| obj.is_a?(Class) } # => array of all classes
Construct a new Exception object, optionally passing in a message.
Create a new SystemExit exception with the given status and message. Status is true, false, or an integer. If status is not given, true is used.
Construct a new SignalException object. sig_name should be a known signal name.
Construct a new KeyError exception with the given message, receiver and key.
Construct a SyntaxError exception.
Construct a new NameError exception. If given the name parameter may subsequently be examined using the NameError#name method. receiver parameter allows to pass object in context of which the error happened. Example:
[1, 2, 3].method(:rject) # NameError with name "rject" and receiver: Array [1, 2, 3].singleton_method(:rject) # NameError with name "rject" and receiver: [1, 2, 3]
Construct a NoMethodError exception for a method of the given name called with the given arguments. The name may be accessed using the name method on the resulting object, and the arguments using the args method.
If private argument were passed, it designates method was attempted to call in private context, and can be accessed with private_call? method.
receiver argument stores an object whose method was called.
Construct a new FrozenError exception. If given the receiver parameter may subsequently be examined using the FrozenError#receiver method.
a = [].freeze raise FrozenError.new("can't modify frozen array", receiver: a)
If errno corresponds to a known system error code, constructs the appropriate Errno class for that error, otherwise constructs a generic SystemCallError object. The error number is subsequently available via the errno method.
Creates a new anonymous module. If a block is given, it is passed the module object, and the block is evaluated in the context of this module like module_eval.
fred = Module.new do def meth1 "hello" end def meth2 "bye" end end a = "my string" a.extend(fred) #=> "my string" a.meth1 #=> "hello" a.meth2 #=> "bye"
Assign the module to a constant (name starting uppercase) if you want to treat it like a regular module.
Creates a DateTime object denoting the given calendar date.
DateTime.new(2001,2,3) #=> #<DateTime: 2001-02-03T00:00:00+00:00 ...> DateTime.new(2001,2,3,4,5,6,'+7') #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...> DateTime.new(2001,-11,-26,-20,-55,-54,'+7') #=> #<DateTime: 2001-02-03T04:05:06+07:00 ...>
Returns a Time object.
It is initialized to the current system time if no argument is given.
Note: The new object will use the resolution available on your system clock, and may include fractional seconds.
If one or more arguments are specified, the time is initialized to the specified time.
sec may have fraction if it is a rational.
tz specifies the timezone. It can be an offset from UTC, given either as a string such as “+09:00” or a single letter “A”..“Z” excluding “J” (so-called military time zone), or as a number of seconds such as 32400. Or it can be a timezone object, see Timezone argument for details.
a = Time.new #=> 2007-11-19 07:50:02 -0600 b = Time.new #=> 2007-11-19 07:50:02 -0600 a == b #=> false "%.6f" % a.to_f #=> "1195480202.282373" "%.6f" % b.to_f #=> "1195480202.283415" Time.new(2008,6,21, 13,30,0, "+09:00") #=> 2008-06-21 13:30:00 +0900 # A trip for RubyConf 2007 t1 = Time.new(2007,11,1,15,25,0, "+09:00") # JST (Narita) t2 = Time.new(2007,11,1,12, 5,0, "-05:00") # CDT (Minneapolis) t3 = Time.new(2007,11,1,13,25,0, "-05:00") # CDT (Minneapolis) t4 = Time.new(2007,11,1,16,53,0, "-04:00") # EDT (Charlotte) t5 = Time.new(2007,11,5, 9,24,0, "-05:00") # EST (Charlotte) t6 = Time.new(2007,11,5,11,21,0, "-05:00") # EST (Detroit) t7 = Time.new(2007,11,5,13,45,0, "-05:00") # EST (Detroit) t8 = Time.new(2007,11,6,17,10,0, "+09:00") # JST (Narita) (t2-t1)/3600.0 #=> 10.666666666666666 (t4-t3)/3600.0 #=> 2.466666666666667 (t6-t5)/3600.0 #=> 1.95 (t8-t7)/3600.0 #=> 13.416666666666666
Open a dbm database with the specified name, which can include a directory path. Any file extensions needed will be supplied automatically by the dbm library. For example, Berkeley DB appends ‘.db’, and GNU gdbm uses two physical files with extensions ‘.dir’ and ‘.pag’.
The mode should be an integer, as for Unix chmod.
The first two forms are used to create a new Struct subclass class_name that can contain a value for each member_name. This subclass can be used to create instances of the structure like any other Class.
If the class_name is omitted an anonymous structure class will be created. Otherwise, the name of this struct will appear as a constant in class Struct, so it must be unique for all Structs in the system and must start with a capital letter. Assigning a structure class to a constant also gives the class the name of the constant.
# Create a structure with a name under Struct Struct.new("Customer", :name, :address) #=> Struct::Customer Struct::Customer.new("Dave", "123 Main") #=> #<struct Struct::Customer name="Dave", address="123 Main"> # Create a structure named by its constant Customer = Struct.new(:name, :address) #=> Customer Customer.new("Dave", "123 Main") #=> #<struct Customer name="Dave", address="123 Main">
If the optional keyword_init keyword argument is set to true, .new takes keyword arguments instead of normal arguments.
Customer = Struct.new(:name, :address, keyword_init: true) Customer.new(name: "Dave", address: "123 Main") #=> #<struct Customer name="Dave", address="123 Main">
If a block is given it will be evaluated in the context of StructClass, passing the created class as a parameter:
Customer = Struct.new(:name, :address) do def greeting "Hello #{name}!" end end Customer.new("Dave", "123 Main").greeting #=> "Hello Dave!"
This is the recommended way to customize a struct. Subclassing an anonymous struct creates an extra anonymous class that will never be used.
The last two forms create a new instance of a struct subclass. The number of value parameters must be less than or equal to the number of attributes defined for the structure. Unset parameters default to nil. Passing more parameters than number of attributes will raise an ArgumentError.
Customer = Struct.new(:name, :address) Customer.new("Dave", "123 Main") #=> #<struct Customer name="Dave", address="123 Main"> Customer["Dave"] #=> #<struct Customer name="Dave", address=nil>
Returns a new IO object (a stream) for the given integer file descriptor fd and mode string. opt may be used to specify parts of mode in a more readable fashion. See also IO.sysopen and IO.for_fd.
IO.new is called by various File and IO opening methods such as IO::open, Kernel#open, and File::open.
When mode is an integer it must be combination of the modes defined in File::Constants (File::RDONLY, File::WRONLY|File::CREAT). See the open(2) man page for more information.
When mode is a string it must be in one of the following forms:
fmode fmode ":" ext_enc fmode ":" ext_enc ":" int_enc fmode ":" "BOM|UTF-*"
fmode is an IO open mode string, ext_enc is the external encoding for the IO and int_enc is the internal encoding.
IO Open Mode Ruby allows the following open modes:
"r" Read-only, starts at beginning of file (default mode).
"r+" Read-write, starts at beginning of file.
"w" Write-only, truncates existing file
to zero length or creates a new file for writing.
"w+" Read-write, truncates existing file to zero length
or creates a new file for reading and writing.
"a" Write-only, each write call appends data at end of file.
Creates a new file for writing if file does not exist.
"a+" Read-write, each write call appends data at end of file.
Creates a new file for reading and writing if file does
not exist.
The following modes must be used separately, and along with one or more of the modes seen above.
"b" Binary file mode
Suppresses EOL <-> CRLF conversion on Windows. And
sets external encoding to ASCII-8BIT unless explicitly
specified.
"t" Text file mode
The exclusive access mode (“x”) can be used together with “w” to ensure the file is created. Errno::EEXIST is raised when it already exists. It may not be supported with all kinds of streams (e.g. pipes).
When the open mode of original IO is read only, the mode cannot be changed to be writable. Similarly, the open mode cannot be changed from write only to readable.
When such a change is attempted the error is raised in different locations according to the platform.
IO Encoding When ext_enc is specified, strings read will be tagged by the encoding when reading, and strings output will be converted to the specified encoding when writing.
When ext_enc and int_enc are specified read strings will be converted from ext_enc to int_enc upon input, and written strings will be converted from int_enc to ext_enc upon output. See Encoding for further details of transcoding on input and output.
If “BOM|UTF-8”, “BOM|UTF-16LE” or “BOM|UTF16-BE” are used, Ruby checks for a Unicode BOM in the input document to help determine the encoding. For UTF-16 encodings the file open mode must be binary. When present, the BOM is stripped and the external encoding from the BOM is used. When the BOM is missing the given Unicode encoding is used as ext_enc. (The BOM-set encoding option is case insensitive, so “bom|utf-8” is also valid.)
opt can be used instead of mode for improved readability. The following keys are supported:
Same as mode parameter
Specifies file open flags as integer. If mode parameter is given, this parameter will be bitwise-ORed.
External encoding for the IO.
Internal encoding for the IO. “-” is a synonym for the default internal encoding.
If the value is nil no conversion occurs.
Specifies external and internal encodings as “extern:intern”.
If the value is truth value, same as “t” in argument mode.
If the value is truth value, same as “b” in argument mode.
If the value is false, the fd will be kept open after this IO instance gets finalized.
Also, opt can have same keys in String#encode for controlling conversion between the external encoding and the internal encoding.
fd = IO.sysopen("/dev/tty", "w") a = IO.new(fd,"w") $stderr.puts "Hello" a.puts "World"
Produces:
Hello World
require 'fcntl' fd = STDERR.fcntl(Fcntl::F_DUPFD) io = IO.new(fd, mode: 'w:UTF-16LE', cr_newline: true) io.puts "Hello, World!" fd = STDERR.fcntl(Fcntl::F_DUPFD) io = IO.new(fd, mode: 'w', cr_newline: true, external_encoding: Encoding::UTF_16LE) io.puts "Hello, World!"
Both of above print “Hello, World!” in UTF-16LE to standard error output with converting EOL generated by puts to CR.
Creates a new GDBM instance by opening a gdbm file named filename. If the file does not exist, a new file with file mode mode will be created. flags may be one of the following:
READER - open as a reader
WRITER - open as a writer
WRCREAT - open as a writer; if the database does not exist, create a new one
NEWDB - open as a writer; overwrite any existing databases
The values WRITER, WRCREAT and NEWDB may be combined with the following values by bitwise or:
SYNC - cause all database operations to be synchronized to the disk
NOLOCK - do not lock the database file
If no flags are specified, the GDBM object will try to open the database file as a writer and will create it if it does not already exist (cf. flag WRCREAT). If this fails (for instance, if another process has already opened the database as a reader), it will try to open the database file as a reader (cf. flag READER).
Creates a new OpenStruct object. By default, the resulting OpenStruct object will have no attributes.
The optional hash, if given, will generate attributes and values (can be a Hash, an OpenStruct or a Struct). For example:
require "ostruct" hash = { "country" => "Australia", :capital => "Canberra" } data = OpenStruct.new(hash) data # => #<OpenStruct country="Australia", capital="Canberra">
Constructs a range using the given begin and end. If the exclude_end parameter is omitted or is false, the range will include the end object; otherwise, it will be excluded.
Constructs a new regular expression from pattern, which can be either a String or a Regexp (in which case that regexp’s options are propagated), and new options may not be specified (a change as of Ruby 1.8).
If options is an Integer, it should be one or more of the constants Regexp::EXTENDED, Regexp::IGNORECASE, and Regexp::MULTILINE, or-ed together. Otherwise, if options is not nil or false, the regexp will be case insensitive.
r1 = Regexp.new('^a-z+:\\s+\w+') #=> /^a-z+:\s+\w+/ r2 = Regexp.new('cat', true) #=> /cat/i r3 = Regexp.new(r2) #=> /cat/i r4 = Regexp.new('dog', Regexp::EXTENDED | Regexp::IGNORECASE) #=> /dog/ix
Creates a new set containing the elements of the given enumerable object.
If a block is given, the elements of enum are preprocessed by the given block.
Set.new([1, 2]) #=> #<Set: {1, 2}> Set.new([1, 2, 1]) #=> #<Set: {1, 2}> Set.new([1, 'c', :s]) #=> #<Set: {1, "c", :s}> Set.new(1..5) #=> #<Set: {1, 2, 3, 4, 5}> Set.new([1, 2, 3]) { |x| x * x } #=> #<Set: {1, 4, 9}>
Calls allocate to create a new object of class’s class, then invokes that object’s initialize method, passing it args. This is the method that ends up getting called whenever an object is constructed using .new.
Creates a new anonymous (unnamed) class with the given superclass (or Object if no parameter is given). You can give a class a name by assigning the class object to a constant.
If a block is given, it is passed the class object, and the block is evaluated in the context of this class like class_eval.
fred = Class.new do def meth1 "hello" end def meth2 "bye" end end a = fred.new #=> #<#<Class:0x100381890>:0x100376b98> a.meth1 #=> "hello" a.meth2 #=> "bye"
Assign the class to a constant (name starting uppercase) if you want to treat it like a regular class.