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diff --git a/ruby_2_2/doc/syntax/literals.rdoc b/ruby_2_2/doc/syntax/literals.rdoc deleted file mode 100644 index aadd574a97..0000000000 --- a/ruby_2_2/doc/syntax/literals.rdoc +++ /dev/null @@ -1,347 +0,0 @@ -= Literals - -Literals create objects you can use in your program. Literals include: - -* Booleans and nil -* Numbers -* Strings -* Symbols -* Arrays -* Hashes -* Ranges -* Regular Expressions -* Procs - -== Booleans and nil - -+nil+ and +false+ are both false values. +nil+ is sometimes used to indicate -"no value" or "unknown" but evaluates to +false+ in conditional expressions. - -+true+ is a true value. All objects except +nil+ and +false+ evaluate to a -true value in conditional expressions. - -(There are also the constants +TRUE+, +FALSE+ and +NIL+, but the lowercase -literal forms are preferred.) - -== Numbers - -You can write integers of any size as follows: - - 1234 - 1_234 - -These numbers have the same value, 1,234. The underscore may be used to -enhance readability for humans. You may place an underscore anywhere in the -number. - -Floating point numbers may be written as follows: - - 12.34 - 1234e-2 - 1.234E1 - -These numbers have the same value, 12.34. You may use underscores in floating -point numbers as well. - -You can use a special prefix to write numbers in decimal, hexadecimal, octal -or binary formats. For decimal numbers use a prefix of <tt>0d</tt>, for -hexadecimal numbers use a prefix of <tt>0x</tt>, for octal numbers use a -prefix of <tt>0</tt> or <tt>0o</tt>, for binary numbers use a prefix of -<tt>0b</tt>. The alphabetic component of the number is not case-sensitive. - -Examples: - - 0d170 - 0D170 - - 0xaa - 0xAa - 0xAA - 0Xaa - 0XAa - 0XaA - - 0252 - 0o252 - 0O252 - - 0b10101010 - 0B10101010 - -All these numbers have the same decimal value, 170. Like integers and floats -you may use an underscore for readability. - -== Strings - -The most common way of writing strings is using <tt>"</tt>: - - "This is a string." - -The string may be many lines long. - -Any internal <tt>"</tt> must be escaped: - - "This string has a quote: \". As you can see, it is escaped" - -Double-quote strings allow escaped characters such as <tt>\n</tt> for -newline, <tt>\t</tt> for tab, etc. The full list of supported escape -sequences are as follows: - - \a bell, ASCII 07h (BEL) - \b backspace, ASCII 08h (BS) - \t horizontal tab, ASCII 09h (TAB) - \n newline (line feed), ASCII 0Ah (LF) - \v vertical tab, ASCII 0Bh (VT) - \f form feed, ASCII 0Ch (FF) - \r carriage return, ASCII 0Dh (CR) - \e escape, ASCII 1Bh (ESC) - \s space, ASCII 20h (SPC) - \\ backslash, \ - \nnn octal bit pattern, where nnn is 1-3 octal digits ([0-7]) - \xnn hexadecimal bit pattern, where nn is 1-2 hexadecimal digits ([0-9a-fA-F]) - \unnnn Unicode character, where nnnn is exactly 4 hexadecimal digits ([0-9a-fA-F]) - \u{nnnn ...} Unicode character(s), where each nnnn is 1-6 hexadecimal digits ([0-9a-fA-F]) - \cx or \C-x control character, where x is an ASCII printable character - \M-x meta character, where x is an ASCII printable character - \M-\C-x meta control character, where x is an ASCII printable character - \M-\cx same as above - \c\M-x same as above - \c? or \C-? delete, ASCII 7Fh (DEL) - -Any other character following a backslash is interpreted as the -character itself. - -Double-quote strings allow interpolation of other values using -<tt>#{...}</tt>: - - "One plus one is two: #{1 + 1}" - -Any expression may be placed inside the interpolated section, but it's best to -keep the expression small for readability. - -Interpolation may be disabled by escaping the "#" character or using -single-quote strings: - - '#{1 + 1}' #=> "\#{1 + 1}" - -In addition to disabling interpolation, single-quoted strings also disable all -escape sequences except for the single-quote (<tt>\'</tt>) and backslash -(<tt>\\\\</tt>). - -You may also create strings using <tt>%</tt>: - - %(1 + 1 is #{1 + 1}) #=> "1 + 1 is 2" - -There are two different types of <tt>%</tt> strings <tt>%q(...)</tt> behaves -like a single-quote string (no interpolation or character escaping) while -<tt>%Q</tt> behaves as a double-quote string. See Percent Strings below for -more discussion of the syntax of percent strings. - -Adjacent string literals are automatically concatenated by the interpreter: - - "con" "cat" "en" "at" "ion" #=> "concatenation" - "This string contains "\ - "no newlines." #=> "This string contains no newlines." - -Any combination of adjacent single-quote, double-quote, percent strings will -be concatenated as long as a percent-string is not last. - - %q{a} 'b' "c" #=> "abc" - "a" 'b' %q{c} #=> NameError: uninitialized constant q - -One more way of writing strings is using <tt>?</tt>: - - ?a #=> "a" - -Basically only one character can be placed after <tt>?</tt>: - - ?abc #=> SyntaxError - -Exceptionally, <tt>\C-</tt>, <tt>\M-</tt> and their combination are allowed -before a character. They mean "control", "meta" and "control-meta" -respectively: - - ?\C-a #=> "\x01" - ?\M-a #=> "\xE1" - ?\M-\C-a #=> "\x81" - ?\C-\M-a #=> "\x81", same as above - -=== Here Documents - -If you are writing a large block of text you may use a "here document" or -"heredoc": - - expected_result = <<HEREDOC - This would contain specially formatted text. - - That might span many lines - HEREDOC - -The heredoc starts on the line following <tt><<HEREDOC</tt> and ends with the -next line that starts with <tt>HEREDOC</tt>. The result includes the ending -newline. - -You may use any identifier with a heredoc, but all-uppercase identifiers are -typically used. - -You may indent the ending identifier if you place a "-" after <tt><<</tt>: - - expected_result = <<-INDENTED_HEREDOC - This would contain specially formatted text. - - That might span many lines - INDENTED_HEREDOC - -Note that the while the closing identifier may be indented, the content is -always treated as if it is flush left. If you indent the content those spaces -will appear in the output. - -A heredoc allows interpolation and escaped characters. You may disable -interpolation and escaping by surrounding the opening identifier with single -quotes: - - expected_result = <<-'EXPECTED' - One plus one is #{1 + 1} - EXPECTED - - p expected_result # prints: "One plus one is \#{1 + 1}\n" - -The identifier may also be surrounded with double quotes (which is the same as -no quotes) or with backticks. When surrounded by backticks the HEREDOC -behaves like Kernel#`: - - puts <<-`HEREDOC` - cat #{__FILE__} - HEREDOC - -To call a method on a heredoc place it after the opening identifier: - - expected_result = <<-EXPECTED.chomp - One plus one is #{1 + 1} - EXPECTED - -You may open multiple heredocs on the same line, but this can be difficult to -read: - - puts(<<-ONE, <<-TWO) - content for heredoc one - ONE - content for heredoc two - TWO - -== Symbols - -A Symbol represents a name inside the ruby interpreter. See Symbol for more -details on what symbols are and when ruby creates them internally. - -You may reference a symbol using a colon: <tt>:my_symbol</tt>. - -You may also create symbols by interpolation: - - :"my_symbol1" - :"my_symbol#{1 + 1}" - -Like strings, a single-quote may be used to disable interpolation: - - :'my_symbol#{1 + 1}' #=> :"my_symbol\#{1 + 1}" - -When creating a Hash there is a special syntax for referencing a Symbol as -well. - -== Arrays - -An array is created using the objects between <tt>[</tt> and <tt>]</tt>: - - [1, 2, 3] - -You may place expressions inside the array: - - [1, 1 + 1, 1 + 2] - [1, [1 + 1, [1 + 2]]] - -See Array for the methods you may use with an array. - -== Hashes - -A hash is created using key-value pairs between <tt>{</tt> and <tt>}</tt>: - - { "a" => 1, "b" => 2 } - -Both the key and value may be any object. - -You can create a hash using symbol keys with the following syntax: - - { a: 1, b: 2 } - -This same syntax is used for keyword arguments for a method. - -See Hash for the methods you may use with a hash. - -== Ranges - -A range represents an interval of values. The range may include or exclude -its ending value. - - (1..2) # includes its ending value - (1...2) # excludes its ending value - -You may create a range of any object. See the Range documentation for details -on the methods you need to implement. - -== Regular Expressions - -A regular expression is created using "/": - - /my regular expression/ - -The regular expression may be followed by flags which adjust the matching -behavior of the regular expression. The "i" flag makes the regular expression -case-insensitive: - - /my regular expression/i - -Interpolation may be used inside regular expressions along with escaped -characters. Note that a regular expression may require additional escaped -characters than a string. - -See Regexp for a description of the syntax of regular expressions. - -== Procs - -A proc can be created with <tt>-></tt>: - - -> { 1 + 1 } - -Calling the above proc will give a result of <tt>2</tt>. - -You can require arguments for the proc as follows: - - ->(v) { 1 + v } - -This proc will add one to its argument. - -== Percent Strings - -Besides <tt>%(...)</tt> which creates a String, The <tt>%</tt> may create -other types of object. As with strings, an uppercase letter allows -interpolation and escaped characters while a lowercase letter disables them. - -These are the types of percent strings in ruby: - -<tt>%i</tt> :: Array of Symbols -<tt>%q</tt> :: String -<tt>%r</tt> :: Regular Expression -<tt>%s</tt> :: Symbol -<tt>%w</tt> :: Array of Strings -<tt>%x</tt> :: Backtick (capture subshell result) - -For the two array forms of percent string, if you wish to include a space in -one of the array entries you must escape it with a "\\" character: - - %w[one one-hundred\ one] - #=> ["one", "one-hundred one"] - -If you are using "(", "[", "{", "<" you must close it with ")", "]", "}", ">" -respectively. You may use most other non-alphanumeric characters for percent -string delimiters such as "%", "|", "^", etc. - |