Returns a pretty printed object as a string.
See the PP module for more information.
With a block given, returns an array of elements of self, sorted according to the value returned by the block for each element. The ordering of equal elements is indeterminate and may be unstable.
Examples:
a = %w[xx xxx x xxxx] a.sort_by {|s| s.size } # => ["x", "xx", "xxx", "xxxx"] a.sort_by {|s| -s.size } # => ["xxxx", "xxx", "xx", "x"] h = {foo: 2, bar: 1, baz: 0} h.sort_by{|key, value| value } # => [[:baz, 0], [:bar, 1], [:foo, 2]] h.sort_by{|key, value| key } # => [[:bar, 1], [:baz, 0], [:foo, 2]]
With no block given, returns an Enumerator.
The current implementation of sort_by generates an array of tuples containing the original collection element and the mapped value. This makes sort_by fairly expensive when the keysets are simple.
require 'benchmark' a = (1..100000).map { rand(100000) } Benchmark.bm(10) do |b| b.report("Sort") { a.sort } b.report("Sort by") { a.sort_by { |a| a } } end
produces:
user system total real Sort 0.180000 0.000000 0.180000 ( 0.175469) Sort by 1.980000 0.040000 2.020000 ( 2.013586)
However, consider the case where comparing the keys is a non-trivial operation. The following code sorts some files on modification time using the basic sort method.
files = Dir["*"] sorted = files.sort { |a, b| File.new(a).mtime <=> File.new(b).mtime } sorted #=> ["mon", "tues", "wed", "thurs"]
This sort is inefficient: it generates two new File objects during every comparison. A slightly better technique is to use the Kernel#test method to generate the modification times directly.
files = Dir["*"] sorted = files.sort { |a, b| test(?M, a) <=> test(?M, b) } sorted #=> ["mon", "tues", "wed", "thurs"]
This still generates many unnecessary Time objects. A more efficient technique is to cache the sort keys (modification times in this case) before the sort. Perl users often call this approach a Schwartzian transform, after Randal Schwartz. We construct a temporary array, where each element is an array containing our sort key along with the filename. We sort this array, and then extract the filename from the result.
sorted = Dir["*"].collect { |f| [test(?M, f), f] }.sort.collect { |f| f[1] } sorted #=> ["mon", "tues", "wed", "thurs"]
This is exactly what sort_by does internally.
sorted = Dir["*"].sort_by { |f| test(?M, f) } sorted #=> ["mon", "tues", "wed", "thurs"]
To produce the reverse of a specific order, the following can be used:
ary.sort_by { ... }.reverse!
With a block given, calls the block with each element, but in reverse order; returns self:
a = [] (1..4).reverse_each {|element| a.push(-element) } # => 1..4 a # => [-4, -3, -2, -1] a = [] %w[a b c d].reverse_each {|element| a.push(element) } # => ["a", "b", "c", "d"] a # => ["d", "c", "b", "a"] a = [] h.reverse_each {|element| a.push(element) } # => {:foo=>0, :bar=>1, :baz=>2} a # => [[:baz, 2], [:bar, 1], [:foo, 0]]
With no block given, returns an Enumerator.
Makes a set from the enumerable object with given arguments.
Returns a hash that contains filename as key and coverage array as value. This is the same as ‘Coverage.result(stop: false, clear: false)`.
{
"file.rb" => [1, 2, nil],
...
}
Sets create identifier, which is used to decide if the json_create hook of a class should be called; initial value is json_class:
JSON.create_id # => 'json_class'
Returns the current create identifier. See also JSON.create_id=.
Arguments obj and opts here are the same as arguments obj and opts in JSON.generate.
By default, generates JSON data without checking for circular references in obj (option max_nesting set to false, disabled).
Raises an exception if obj contains circular references:
a = []; b = []; a.push(b); b.push(a) # Raises SystemStackError (stack level too deep): JSON.fast_generate(a)
Arguments obj and opts here are the same as arguments obj and opts in JSON.generate.
Default options are:
{
indent: ' ', # Two spaces
space: ' ', # One space
array_nl: "\n", # Newline
object_nl: "\n" # Newline
}
Example:
obj = {foo: [:bar, :baz], bat: {bam: 0, bad: 1}} json = JSON.pretty_generate(obj) puts json
Output:
{
"foo": [
"bar",
"baz"
],
"bat": {
"bam": 0,
"bad": 1
}
}
Turns FIPS mode on or off. Turning on FIPS mode will obviously only have an effect for FIPS-capable installations of the OpenSSL library. Trying to do so otherwise will result in an error.
OpenSSL.fips_mode = true # turn FIPS mode on OpenSSL.fips_mode = false # and off again
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.
If file_name is writable 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_writable?("/tmp") #=> 511 m = File.world_writable?("/tmp") sprintf("%o", m) #=> "777"
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.
Returns information for heaps in the GC.
If the first optional argument, heap_name, is passed in and not nil, it returns a Hash containing information about the particular heap. Otherwise, it will return a Hash with heap names as keys and a Hash containing information about the heap as values.
If the second optional argument, hash_or_key, is given as a Hash, it will be overwritten and returned. This is intended to avoid the probe effect.
If both optional arguments are passed in and the second optional argument is a symbol, it will return a Numeric value for the particular heap.
On CRuby, heap_name is of the type Integer but may be of type String on other implementations.
The contents of the hash are implementation-specific and may change in the future without notice.
If the optional argument, hash, is given, it is overwritten and returned.
This method is only expected to work on CRuby.
The hash includes the following keys about the internal information in the GC:
The slot size of the heap in bytes.
The number of pages that can be allocated without triggering a new garbage collection cycle.
The number of pages in the eden heap.
The total number of slots in all of the pages in the eden heap.
The number of pages in the tomb heap. The tomb heap only contains pages that do not have any live objects.
The total number of slots in all of the pages in the tomb heap.
The total number of pages that have been allocated in the heap.
The total number of pages that have been freed and released back to the system in the heap.
The number of times this heap has forced major garbage collection cycles to start due to running out of free slots.
The number of times this heap has forced incremental marking to complete due to running out of pooled slots.
Returns the measured GC total time in nanoseconds.
Adds a post-build hook that will be passed an Gem::Installer instance when Gem::Installer#install is called. The hook is called after the gem has been extracted and extensions have been built but before the executables or gemspec has been written. If the hook returns false then the gem’s files will be removed and the install will be aborted.
Adds a post-installs hook that will be passed a Gem::DependencyInstaller and a list of installed specifications when Gem::DependencyInstaller#install is complete
Safely read a file in binary mode on all platforms.
Regexp for require-able path suffixes.
Is this a windows platform?
Is this a java platform?