Switch the effective and real user IDs of the current process. If a block is given, the user IDs will be switched back after the block is executed. Returns the new effective user ID if called without a block, and the return value of the block if one is given.
Switch the effective and real group IDs of the current process. If a block is given, the group IDs will be switched back after the block is executed. Returns the new effective group ID if called without a block, and the return value of the block if one is given.
Calls the block with each repeated permutation of length n of the elements of self; each permutation is an Array; returns self. The order of the permutations is indeterminate.
When a block and a positive Integer argument n are given, calls the block with each n-tuple repeated permutation of the elements of self. The number of permutations is self.size**n.
n = 1:
a = [0, 1, 2] a.repeated_permutation(1) {|permutation| p permutation }
Output:
[0] [1] [2]
n = 2:
a.repeated_permutation(2) {|permutation| p permutation }
Output:
[0, 0] [0, 1] [0, 2] [1, 0] [1, 1] [1, 2] [2, 0] [2, 1] [2, 2]
If n is zero, calls the block once with an empty Array.
If n is negative, does not call the block:
a.repeated_permutation(-1) {|permutation| fail 'Cannot happen' }
Returns a new Enumerator if no block given:
a = [0, 1, 2] a.repeated_permutation(2) # => #<Enumerator: [0, 1, 2]:permutation(2)>
Using Enumerators, it’s convenient to show the permutations and counts for some values of n:
e = a.repeated_permutation(0) e.size # => 1 e.to_a # => [[]] e = a.repeated_permutation(1) e.size # => 3 e.to_a # => [[0], [1], [2]] e = a.repeated_permutation(2) e.size # => 9 e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 0], [1, 1], [1, 2], [2, 0], [2, 1], [2, 2]]
Calls the block with each repeated combination of length n of the elements of self; each combination is an Array; returns self. The order of the combinations is indeterminate.
When a block and a positive Integer argument n are given, calls the block with each n-tuple repeated combination of the elements of self. The number of combinations is (n+1)(n+2)/2.
n = 1:
a = [0, 1, 2] a.repeated_combination(1) {|combination| p combination }
Output:
[0] [1] [2]
n = 2:
a.repeated_combination(2) {|combination| p combination }
Output:
[0, 0] [0, 1] [0, 2] [1, 1] [1, 2] [2, 2]
If n is zero, calls the block once with an empty Array.
If n is negative, does not call the block:
a.repeated_combination(-1) {|combination| fail 'Cannot happen' }
Returns a new Enumerator if no block given:
a = [0, 1, 2] a.repeated_combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
Using Enumerators, it’s convenient to show the combinations and counts for some values of n:
e = a.repeated_combination(0) e.size # => 1 e.to_a # => [[]] e = a.repeated_combination(1) e.size # => 3 e.to_a # => [[0], [1], [2]] e = a.repeated_combination(2) e.size # => 6 e.to_a # => [[0, 0], [0, 1], [0, 2], [1, 1], [1, 2], [2, 2]]
Passes each character in str to the given block, or returns an enumerator if no block is given.
"hello".each_char {|c| print c, ' ' }
produces:
h e l l o
Calls the block once for each entry except for “.” and “..” in the named directory, passing the filename of each entry as a parameter to the block.
If no block is given, an enumerator is returned instead.
Dir.each_child("testdir") {|x| puts "Got #{x}" }
produces:
Got config.h Got main.rb
Calls the block once for each entry except for “.” and “..” in this directory, passing the filename of each entry as a parameter to the block.
If no block is given, an enumerator is returned instead.
d = Dir.new("testdir") d.each_child {|x| puts "Got #{x}" }
produces:
Got config.h Got main.rb
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.
Calls the given block once for each character in ios, passing the character as an argument. The stream must be opened for reading or an IOError will be raised.
If no block is given, an enumerator is returned instead.
f = File.new("testfile") f.each_char {|c| print c, ' ' } #=> #<File:testfile>
Iterates over the children of the directory (files and subdirectories, not recursive).
It yields Pathname object for each child.
By default, the yielded pathnames will have enough information to access the files.
If you set with_directory to false, then the returned pathnames will contain the filename only.
Pathname("/usr/local").each_child {|f| p f } #=> #<Pathname:/usr/local/share> # #<Pathname:/usr/local/bin> # #<Pathname:/usr/local/games> # #<Pathname:/usr/local/lib> # #<Pathname:/usr/local/include> # #<Pathname:/usr/local/sbin> # #<Pathname:/usr/local/src> # #<Pathname:/usr/local/man> Pathname("/usr/local").each_child(false) {|f| p f } #=> #<Pathname:share> # #<Pathname:bin> # #<Pathname:games> # #<Pathname:lib> # #<Pathname:include> # #<Pathname:sbin> # #<Pathname:src> # #<Pathname:man>
Note that the results never contain the entries . and .. in the directory because they are not children.
Returns a new Array containing the values associated with the given keys *keys:
h = {foo: 0, bar: 1, baz: 2} h.fetch_values(:baz, :foo) # => [2, 0]
Returns a new empty Array if no arguments given.
When a block is given, calls the block with each missing key, treating the block’s return value as the value for that key:
h = {foo: 0, bar: 1, baz: 2} values = h.fetch_values(:bar, :foo, :bad, :bam) {|key| key.to_s} values # => [1, 0, "bad", "bam"]
When no block is given, raises an exception if any given key is not found.
Iterates over each character of each file in ARGF.
This method allows you to treat the files supplied on the command line as a single file consisting of the concatenation of each named file. After the last character of the first file has been returned, the first character of the second file is returned. The ARGF.filename method can be used to determine the name of the file in which the current character appears.
If no block is given, an enumerator is returned instead.
Explicit conversion to a Matrix. Returns self
Return a single-column matrix from this vector
This is similar to PrettyPrint::format but the result has no breaks.
maxwidth, newline and genspace are ignored.
The invocation of breakable in the block doesn’t break a line and is treated as just an invocation of text.
Returns a new array with the concatenated results of running block once for every element in enum.
If no block is given, an enumerator is returned instead.
[1, 2, 3, 4].flat_map { |e| [e, -e] } #=> [1, -1, 2, -2, 3, -3, 4, -4] [[1, 2], [3, 4]].flat_map { |e| e + [100] } #=> [1, 2, 100, 3, 4, 100]
Returns a two element array containing the objects in enum that correspond to the minimum and maximum values respectively from the given block.
If no block is given, an enumerator is returned instead.
a = %w(albatross dog horse) a.minmax_by { |x| x.length } #=> ["dog", "albatross"]
Returns garbage collector generation for the given object.
class B include ObjectSpace def foo trace_object_allocations do obj = Object.new p "Generation is #{allocation_generation(obj)}" end end end B.new.foo #=> "Generation is 3"
See ::trace_object_allocations for more information and examples.
Returns the number of malloc() allocations.
Only available if ruby was built with CALC_EXACT_MALLOC_SIZE.
Retrieves the server with the given uri.
See also regist_server and remove_server.
Generates the Makefile for your extension, passing along any options and preprocessor constants that you may have generated through other methods.
The target name should correspond the name of the global function name defined within your C extension, minus the Init_. For example, if your C extension is defined as Init_foo, then your target would simply be “foo”.
If any “/” characters are present in the target name, only the last name is interpreted as the target name, and the rest are considered toplevel directory names, and the generated Makefile will be altered accordingly to follow that directory structure.
For example, if you pass “test/foo” as a target name, your extension will be installed under the “test” directory. This means that in order to load the file within a Ruby program later, that directory structure will have to be followed, e.g. require 'test/foo'.
The srcprefix should be used when your source files are not in the same directory as your build script. This will not only eliminate the need for you to manually copy the source files into the same directory as your build script, but it also sets the proper target_prefix in the generated Makefile.
Setting the target_prefix will, in turn, install the generated binary in a directory under your RbConfig::CONFIG['sitearchdir'] that mimics your local filesystem when you run make install.
For example, given the following file tree:
ext/ extconf.rb test/ foo.c
And given the following code:
create_makefile('test/foo', 'test')
That will set the target_prefix in the generated Makefile to “test”. That, in turn, will create the following file tree when installed via the make install command:
/path/to/ruby/sitearchdir/test/foo.so
It is recommended that you use this approach to generate your makefiles, instead of copying files around manually, because some third party libraries may depend on the target_prefix being set properly.
The srcprefix argument can be used to override the default source directory, i.e. the current directory. It is included as part of the VPATH and added to the list of INCFLAGS.