Returns a new Array containing zero or more trailing elements of self; does not modify self.
With a block given, calls the block with each successive element of self; stops if the block returns false or nil; returns a new Array omitting those elements for which the block returned a truthy value:
a = [0, 1, 2, 3, 4, 5] a.drop_while {|element| element < 3 } # => [3, 4, 5]
With no block given, returns a new Enumerator:
[0, 1].drop_while # => # => #<Enumerator: [0, 1]:drop_while>
Returns a copy of self with leading substring prefix removed:
'hello'.delete_prefix('hel') # => "lo" 'hello'.delete_prefix('llo') # => "hello" 'тест'.delete_prefix('те') # => "ст" 'こんにちは'.delete_prefix('こん') # => "にちは"
Related: String#delete_prefix!, String#delete_suffix.
Like String#delete_prefix, except that self is modified in place. Returns self if the prefix is removed, nil otherwise.
Returns the next-smaller representable Float.
These examples show the internally stored values (64-bit hexadecimal) for each Float f and for the corresponding f.pev_float:
f = 5e-324 # 0x0000000000000001 f.prev_float # 0x0000000000000000 f = 0.01 # 0x3f847ae147ae147b f.prev_float # 0x3f847ae147ae147a
In the remaining examples here, the output is shown in the usual way (result to_s):
0.01.prev_float # => 0.009999999999999998 1.0.prev_float # => 0.9999999999999999 100.0.prev_float # => 99.99999999999999 f = 0.01 (0..3).each_with_index {|i| printf "%2d %-20a %s\n", i, f, f.to_s; f = f.prev_float }
Output:
0 0x1.47ae147ae147bp-7 0.01 1 0x1.47ae147ae147ap-7 0.009999999999999998 2 0x1.47ae147ae1479p-7 0.009999999999999997 3 0x1.47ae147ae1478p-7 0.009999999999999995
Related: Float#next_float.
Like backtrace, but returns each line of the execution stack as a Thread::Backtrace::Location. Accepts the same arguments as backtrace.
f = Fiber.new { Fiber.yield } f.resume loc = f.backtrace_locations.first loc.label #=> "yield" loc.path #=> "test.rb" loc.lineno #=> 1
Returns the locale charmap name. It returns nil if no appropriate information.
Debian GNU/Linux LANG=C Encoding.locale_charmap #=> "ANSI_X3.4-1968" LANG=ja_JP.EUC-JP Encoding.locale_charmap #=> "EUC-JP" SunOS 5 LANG=C Encoding.locale_charmap #=> "646" LANG=ja Encoding.locale_charmap #=> "eucJP"
The result is highly platform dependent. So Encoding.find(Encoding.locale_charmap) may cause an error. If you need some encoding object even for unknown locale, Encoding.find(“locale”) can be used.
Returns the list of private methods accessible to obj. If the all parameter is set to false, only those methods in the receiver will be listed.
Returns any backtrace associated with the exception. This method is similar to Exception#backtrace, but the backtrace is an array of Thread::Backtrace::Location.
This method is not affected by Exception#set_backtrace().
Return a list of the local variable names defined where this NameError exception was raised.
Internal use only.
Return true if the caused method was called as private.
When this module is prepended in another, Ruby calls prepend_features in this module, passing it the receiving module in mod. Ruby’s default implementation is to overlay the constants, methods, and module variables of this module to mod if this module has not already been added to mod or one of its ancestors. See also Module#prepend.
Makes a list of existing constants private.
Makes a list of existing constants deprecated. Attempt to refer to them will produce a warning.
module HTTP NotFound = Exception.new NOT_FOUND = NotFound # previous version of the library used this name deprecate_constant :NOT_FOUND end HTTP::NOT_FOUND # warning: constant HTTP::NOT_FOUND is deprecated
Returns a 2-length array; the first item is the result of BigDecimal#precision and the second one is of BigDecimal#scale.
See BigDecimal#precision. See BigDecimal#scale.
Equivalent to Date#- with argument n.
Equivalent to << with argument n.
Equivalent to << with argument n * 12.
Waits until IO is priority and returns a truthy value or a falsy value when times out. Priority data is sent and received using the Socket::MSG_OOB flag and is typically limited to streams.
You must require ‘io/wait’ to use this method.
Reads at most maxlen bytes from ios using the read(2) system call after O_NONBLOCK is set for the underlying file descriptor.
If the optional outbuf argument is present, it must reference a String, which will receive the data. The outbuf will contain only the received data after the method call even if it is not empty at the beginning.
read_nonblock just calls the read(2) system call. It causes all errors the read(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc. The caller should care such errors.
If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, it is extended by IO::WaitReadable. So IO::WaitReadable can be used to rescue the exceptions for retrying read_nonblock.
read_nonblock causes EOFError on EOF.
On some platforms, such as Windows, non-blocking mode is not supported on IO objects other than sockets. In such cases, Errno::EBADF will be raised.
If the read byte buffer is not empty, read_nonblock reads from the buffer like readpartial. In this case, the read(2) system call is not called.
When read_nonblock raises an exception kind of IO::WaitReadable, read_nonblock should not be called until io is readable for avoiding busy loop. This can be done as follows.
# emulates blocking read (readpartial). begin result = io.read_nonblock(maxlen) rescue IO::WaitReadable IO.select([io]) retry end
Although IO#read_nonblock doesn’t raise IO::WaitWritable. OpenSSL::Buffering#read_nonblock can raise IO::WaitWritable. If IO and SSL should be used polymorphically, IO::WaitWritable should be rescued too. See the document of OpenSSL::Buffering#read_nonblock for sample code.
Note that this method is identical to readpartial except the non-blocking flag is set.
By specifying a keyword argument exception to false, you can indicate that read_nonblock should not raise an IO::WaitReadable exception, but return the symbol :wait_readable instead. At EOF, it will return nil instead of raising EOFError.
Writes the given string to ios using the write(2) system call after O_NONBLOCK is set for the underlying file descriptor.
It returns the number of bytes written.
write_nonblock just calls the write(2) system call. It causes all errors the write(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc. The result may also be smaller than string.length (partial write). The caller should care such errors and partial write.
If the exception is Errno::EWOULDBLOCK or Errno::EAGAIN, it is extended by IO::WaitWritable. So IO::WaitWritable can be used to rescue the exceptions for retrying write_nonblock.
# Creates a pipe. r, w = IO.pipe # write_nonblock writes only 65536 bytes and return 65536. # (The pipe size is 65536 bytes on this environment.) s = "a" * 100000 p w.write_nonblock(s) #=> 65536 # write_nonblock cannot write a byte and raise EWOULDBLOCK (EAGAIN). p w.write_nonblock("b") # Resource temporarily unavailable (Errno::EAGAIN)
If the write buffer is not empty, it is flushed at first.
When write_nonblock raises an exception kind of IO::WaitWritable, write_nonblock should not be called until io is writable for avoiding busy loop. This can be done as follows.
begin result = io.write_nonblock(string) rescue IO::WaitWritable, Errno::EINTR IO.select(nil, [io]) retry end
Note that this doesn’t guarantee to write all data in string. The length written is reported as result and it should be checked later.
On some platforms such as Windows, write_nonblock is not supported according to the kind of the IO object. In such cases, write_nonblock raises Errno::EBADF.
By specifying a keyword argument exception to false, you can indicate that write_nonblock should not raise an IO::WaitWritable exception, but return the symbol :wait_writable instead.