@param [String] requirement_name the spec name to search for @return [Object] the locked spec named ‘requirement_name`, if one
is found on {#base}
Returns a copy of str with leading prefix
deleted.
"hello".delete_prefix("hel") #=> "lo" "hello".delete_prefix("llo") #=> "hello"
Deletes leading prefix
from str, returning nil
if no change was made.
"hello".delete_prefix!("hel") #=> "lo" "hello".delete_prefix!("llo") #=> nil
Returns the previous representable floating point number.
(-Float::MAX).prev_float and (-Float::INFINITY).prev_float is -Float::INFINITY.
Float::NAN.prev_float is Float::NAN
.
For example:
0.01.prev_float #=> 0.009999999999999998 1.0.prev_float #=> 0.9999999999999999 100.0.prev_float #=> 99.99999999999999 0.01 - 0.01.prev_float #=> 1.734723475976807e-18 1.0 - 1.0.prev_float #=> 1.1102230246251565e-16 100.0 - 100.0.prev_float #=> 1.4210854715202004e-14 f = 0.01; 20.times { printf "%-20a %s\n", f, f.to_s; f = f.prev_float } #=> 0x1.47ae147ae147bp-7 0.01 # 0x1.47ae147ae147ap-7 0.009999999999999998 # 0x1.47ae147ae1479p-7 0.009999999999999997 # 0x1.47ae147ae1478p-7 0.009999999999999995 # 0x1.47ae147ae1477p-7 0.009999999999999993 # 0x1.47ae147ae1476p-7 0.009999999999999992 # 0x1.47ae147ae1475p-7 0.00999999999999999 # 0x1.47ae147ae1474p-7 0.009999999999999988 # 0x1.47ae147ae1473p-7 0.009999999999999986 # 0x1.47ae147ae1472p-7 0.009999999999999985 # 0x1.47ae147ae1471p-7 0.009999999999999983 # 0x1.47ae147ae147p-7 0.009999999999999981 # 0x1.47ae147ae146fp-7 0.00999999999999998 # 0x1.47ae147ae146ep-7 0.009999999999999978 # 0x1.47ae147ae146dp-7 0.009999999999999976 # 0x1.47ae147ae146cp-7 0.009999999999999974 # 0x1.47ae147ae146bp-7 0.009999999999999972 # 0x1.47ae147ae146ap-7 0.00999999999999997 # 0x1.47ae147ae1469p-7 0.009999999999999969 # 0x1.47ae147ae1468p-7 0.009999999999999967
If file_name is readable by others, returns an integer representing the file permission bits of file_name. Returns nil
otherwise. The meaning of the bits is platform dependent; on Unix systems, see stat(2)
.
file_name can be an IO
object.
File.world_readable?("/etc/passwd") #=> 420 m = File.world_readable?("/etc/passwd") sprintf("%o", m) #=> "644"
Returns true
if the named file is writable by the real user and group id of this process. See access(3).
Note that some OS-level security features may cause this to return true even though the file is not writable by the real user/group.
Returns true
if the named file is executable by the real user and group id of this process. See access(3).
Windows does not support execute permissions separately from read permissions. On Windows, a file is only considered executable if it ends in .bat, .cmd, .com, or .exe.
Note that some OS-level security features may cause this to return true even though the file is not executable by the real user/group.
When this module is included in another, Ruby calls append_features
in this module, passing it the receiving module in mod. Ruby’s default implementation is to add 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#include
.
Returns an array of all modules used in the current scope. The ordering of modules in the resulting array is not defined.
module A refine Object do end end module B refine Object do end end using A using B p Module.used_modules
produces:
[B, A]
Returns the list of modules included in mod.
module Mixin end module Outer include Mixin end Mixin.included_modules #=> [] Outer.included_modules #=> [Mixin]
Creates instance variables and corresponding methods that return the value of each instance variable. Equivalent to calling “attr
:name” on each name in turn. String
arguments are converted to symbols.
Evaluates the given block in the context of the class/module. The method defined in the block will belong to the receiver. Any arguments passed to the method will be passed to the block. This can be used if the block needs to access instance variables.
class Thing end Thing.class_exec{ def hello() "Hello there!" end } puts Thing.new.hello()
produces:
Hello there!
Evaluates the string or block in the context of mod, except that when a block is given, constant/class variable lookup is not affected. This can be used to add methods to a class. module_eval
returns the result of evaluating its argument. The optional filename and lineno parameters set the text for error messages.
class Thing end a = %q{def hello() "Hello there!" end} Thing.module_eval(a) puts Thing.new.hello() Thing.module_eval("invalid code", "dummy", 123)
produces:
Hello there! dummy:123:in `module_eval': undefined local variable or method `code' for Thing:Class
Execute the provided block, but preserve the precision limit
BigDecimal.limit(100) puts BigDecimal.limit BigDecimal.save_limit do BigDecimal.limit(200) puts BigDecimal.limit end puts BigDecimal.limit
Returns true if the given year is a leap year of the proleptic Gregorian calendar.
Date.gregorian_leap?(1900) #=> false Date.gregorian_leap?(2000) #=> true
This method is equivalent to d - n.
This method is equivalent to d << (n * 12).
Date.new(2001,2,3).prev_year #=> #<Date: 2000-02-03 ...> Date.new(2008,2,29).prev_year #=> #<Date: 2007-02-28 ...> Date.new(2008,2,29).prev_year(4) #=> #<Date: 2004-02-29 ...>
See also Date#<<
.
Waits until IO
is readable without blocking and returns self
, or nil
when times out. Returns true
immediately when buffered data is available.
Closes the read end of a duplex I/O stream (i.e., one that contains both a read and a write stream, such as a pipe). Will raise an IOError
if the stream is not duplexed.
f = IO.popen("/bin/sh","r+") f.close_read f.readlines
produces:
prog.rb:3:in `readlines': not opened for reading (IOError) from prog.rb:3
Calling this method on closed IO
object is just ignored since Ruby 2.3.
Returns a hash representing information about named captures of rxp.
A key of the hash is a name of the named captures. A value of the hash is an array which is list of indexes of corresponding named captures.
/(?<foo>.)(?<bar>.)/.named_captures #=> {"foo"=>[1], "bar"=>[2]} /(?<foo>.)(?<foo>.)/.named_captures #=> {"foo"=>[1, 2]}
If there are no named captures, an empty hash is returned.
/(.)(.)/.named_captures #=> {}