Difference between revisions of "Ruby Info"
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=Language= | =Language= | ||
General Tips | ==General Tips== | ||
These are tips I've given over and over and over and over... | These are tips I've given over and over and over and over... | ||
Use 2 space indent, no tabs. | * Use 2 space indent, no tabs. | ||
* dontNameVarsCamelCase, use_readable_variables. | |||
* use [] over Array.new. | |||
* and {} over Hash.new. | |||
* don't rescue Exception. EVER. or I will stab you. | |||
* don't call exit inside of a library method. | |||
* use space more. | |||
* use globals less. | |||
* use parens to disambiguate, otherwise avoid them. | |||
* use Enumerable.map instead of reimplementing it with each. | |||
* returning different types is almost always a no-no. | |||
* hungarian notation is for Other Languages, not Ruby. | |||
* separate ideas with blank lines, just like paragraphs. | |||
* align stuff to be cleaner and to optimize for human pattern matching. | |||
* See github.com /chneukirchen /styleguide /raw /master /RUBY-STYLE for more. | |||
==General Syntax Rules== | |||
<pre> | |||
Comments start with a pound/sharp (#) character and go to EOL. | Comments start with a pound/sharp (#) character and go to EOL. | ||
Ruby programs are sequence of expressions. | Ruby programs are sequence of expressions. |
Latest revision as of 00:26, 21 May 2011
See - http://www.zenspider.com/Languages/Ruby/QuickRef.html
Ruby QuickRef
Language
General Tips
These are tips I've given over and over and over and over...
- Use 2 space indent, no tabs.
- dontNameVarsCamelCase, use_readable_variables.
- use [] over Array.new.
- and {} over Hash.new.
- don't rescue Exception. EVER. or I will stab you.
- don't call exit inside of a library method.
- use space more.
- use globals less.
- use parens to disambiguate, otherwise avoid them.
- use Enumerable.map instead of reimplementing it with each.
- returning different types is almost always a no-no.
- hungarian notation is for Other Languages, not Ruby.
- separate ideas with blank lines, just like paragraphs.
- align stuff to be cleaner and to optimize for human pattern matching.
- See github.com /chneukirchen /styleguide /raw /master /RUBY-STYLE for more.
General Syntax Rules
Comments start with a pound/sharp (#) character and go to EOL. Ruby programs are sequence of expressions. Each expression is delimited by semicolons(;) or newlines unless obviously incomplete (e.g. trailing '+'). Backslashes at the end of line does not terminate expression. Reserved words alias and BEGIN begin break case class def defined? do else elsif END end ensure false for if in module next nil not or redo rescue retry return self super then true undef unless until when while yield Types Basic types are numbers, strings, ranges, regexen, symbols, arrays, and hashes. Also included are files because they are used so often. Numbers 123 1_234 123.45 1.2e-3 0xffff (hex) 0b01011 (binary) 0377 (octal) ?a ASCII character ?\C-a Control-a ?\M-a Meta-a ?\M-\C-a Meta-Control-a Strings In all of the %() cases below, you may use any matching characters or any single character for delimiters. %[], %!!, %@@, etc. 'no interpolation' "#{interpolation}, and backslashes\n" %q(no interpolation) %Q(interpolation and backslashes) %(interpolation and backslashes) `echo command interpretation with interpolation and backslashes` %x(echo command interpretation with interpolation and backslashes) Backslashes \t (tab), \n (newline), \r (carriage return), \f (form feed), \b (backspace), \a (bell), \e (escape), \s (whitespace), \nnn (octal), \xnn (hexadecimal), \cx (control x), \C-x (control x), \M-x (meta x), \M-\C-x (meta control x) Here Docs <<identifier - interpolated, goes until identifier <<"identifier" - same thing <<'identifier' - no interpolation <<-identifier - you can indent the identifier by using "-" in front Symbols Internalized String. Guaranteed to be unique and quickly comparable. Ideal for hash keys. Symbols may not contain \0 or be empty. :symbol => :symbol :'#{"without"} interpolation' => :"#{"without"} interpolation" :"#{"with"} interpolation" => :"with interpolation" %s(#{"without"} interpolation) => :"#{"without"} interpolation" Ranges 1..10 1...10 'a'..'z' 'a'...'z' (1..10) === 5 => true (1..10) === 10 => true (1...10) === 10 => false (1..10) === 15 => false while gets # prints lines starting at 'start' and ending at 'end' print if /start/../end/ end class Comparable # ... def <=>(rhs) # ... end def succ # ... end end range = RangeThingy.new(lower_bound)..RangeThingy.new(upper_bound) Regexen Test out your regexen in irb or on: www.rubyxp.com Usual recommended form: str =~ /regex/ Lexical options: /normal regex/iomx[neus] %rXalternate formX (where X can be any character or pair () {} etc) options: /i case insensitive /o only interpolate #{} blocks once /m multiline mode - '.' will match newline /x extended mode - whitespace is ignored /[neus] encoding: none, EUC, UTF-8, SJIS, respectively regex characters: . any character except newline [ ] any single character of set [^ ] any single character NOT of set * 0 or more previous regular expression *? 0 or more previous regular expression (non-greedy) + 1 or more previous regular expression +? 1 or more previous regular expression (non-greedy) ? 0 or 1 previous regular expression | alternation ( ) grouping regular expressions ^ beginning of a line or string $ end of a line or string {m,n} at least m but most n previous regular expression {m,n}? at least m but most n previous regular expression (non-greedy) \1-9 nth previous captured group \& whole match \` pre-match \' post-match \+ highest group matched \A beginning of a string \b backspace(0x08)(inside[]only) \b word boundary(outside[]only) \B non-word boundary \d digit, same as[0-9] \D non-digit \S non-whitespace character \s whitespace character[ \t\n\r\f] \W non-word character \w word character[0-9A-Za-z_] \z end of a string \Z end of a string, or before newline at the end (?#) comment (?:) grouping without backreferences (?=) zero-width positive look-ahead assertion (?!) zero-width negative look-ahead assertion (?>) nested anchored sub-regexp. stops backtracking. (?imx-imx) turns on/off imx options for rest of regexp. (?imx-imx:re) turns on/off imx options, localized in group. special character classes: [:alnum:] alpha-numeric characters [:alpha:] alphabetic characters [:blank:] whitespace - does not include tabs, carriage returns, etc [:cntrl:] control characters [:digit:] decimal digits [:graph:] graph characters [:lower:] lower case characters [:print:] printable characters [:punct:] punctuation characters [:space:] whitespace, including tabs, carriage returns, etc [:upper:] upper case characters [:xdigit:] hexadecimal digits Arrays [1, 2, 3] %w(foo bar baz) %W(foo bar baz #{var}) Indexes may be negative, and they index backwards (eg -1 is last element). Hashes {1=>2, 2=>4, 3=>6} { expr => expr...} Files Common methods include: File.join(p1, p2, ... pN) => "p1/p2/.../pN" platform independent paths File.new(path, modestring="r") => file File.new(path, modenum [, permnum]) => file File.open(fileName, aModeString="r") {|file| block} -> nil File.open(fileName [, aModeNum [, aPermNum ]]) {|file| block} -> nil IO.foreach(path, sepstring=$/) {|line| block} IO.readlines(path) => array Mode Strings r Read-only, starts at beginning of file (default mode). r+ Read-write, starts at beginning of file. w Write-only, truncates existing file to zero length or creates a new file for writing. w+ Read-write, truncates existing file to zero length or creates a new file for reading and writing. a Write-only, starts at end of file if file exists, otherwise creates a new file for writing. a+ Read-write, starts at end of file if file exists, otherwise creates a new file for reading and writing. b (DOS/Windows only) Binary file mode (may appear with any of the key letters listed above). Variables $global_variable @@class_variable @instance_variable [OtherClass::]CONSTANT local_variable Pseudo variables self the receiver of the current method nil the sole instance of the Class NilClass(represents false) true the sole instance of the Class TrueClass(typical true value) false the sole instance of the Class FalseClass(represents false) __FILE__ the current source file name. __LINE__ the current line number in the source file. Pre-defined variables $! The exception information message set by 'raise'. $@ Array of backtrace of the last exception thrown. $& The string matched by the last successful match. $` The string to the left of the last successful match. $' The string to the right of the last successful match. $+ The highest group matched by the last successful match. $1 The Nth group of the last successful match. May be > 1. $~ The information about the last match in the current scope. $= The flag for case insensitive, nil by default. $/ The input record separator, newline by default. $\ The output record separator for the print and IO#write. Default is nil. $, The output field separator for the print and Array#join. $; The default separator for String#split. $. The current input line number of the last file that was read. $< The virtual concatenation file of the files given on command line (or from $stdin if no files were given). $> The default output for print, printf. $stdout by default. $_ The last input line of string by gets or readline. $0 Contains the name of the script being executed. May be assignable. $* Command line arguments given for the script sans args. $$ The process number of the Ruby running this script. $? The status of the last executed child process. $: Load path for scripts and binary modules by load or require. $" The array contains the module names loaded by require. $DEBUG The status of the -d switch. $FILENAME Current input file from $<. Same as $<.filename. $LOAD_PATH The alias to the $:. $stderr The current standard error output. $stdin The current standard input. $stdout The current standard output. $VERBOSE The verbose flag, which is set by the -v switch. $-0 The alias to $/. $-a True if option -a is set. Read-only variable. $-d The alias to $DEBUG. $-F The alias to $;. $-i In in-place-edit mode, this variable holds the extension, otherwise nil. $-I The alias to $:. $-l True if option -l is set. Read-only variable. $-p True if option -p is set. Read-only variable. $-v The alias to $VERBOSE. $-w True if option -w is set. Pre-defined global constants TRUE The typical true value. FALSE The false itself. NIL The nil itself. STDIN The standard input. The default value for $stdin. STDOUT The standard output. The default value for $stdout. STDERR The standard error output. The default value for $stderr. ENV The hash contains current environment variables. ARGF The alias to the $<. ARGV The alias to the $*. DATA The file object of the script, pointing just after __END__. RUBY_VERSION The ruby version string (VERSION was deprecated). RUBY_RELEASE_DATE The release date string. RUBY_PLATFORM The platform identifier. Expressions Terms Terms are expressions that may be a basic type (listed above), a shell command, variable reference, constant reference, or method invocation. Operators and Precedence (Top to bottom) :: . [] ** -(unary) +(unary) ! ~ * / % + - << >> & | ^ > >= < <= <=> == === != =~ !~ && || .. ... =(+=, -=...) not and or All of the above are just methods except these: =, ::, ., .., ..., !, not, &&, and, ||, or, !=, !~ In addition, assignment operators(+= etc.) are not user-definable. NOTE: 1.9 has a horrible extension to allow you to define != and !~. A special place in hell is reserved for you if you define those. Control Expressions if bool-expr [then] body elsif bool-expr [then] body else body end unless bool-expr [then] body else body end expr if bool-expr expr unless bool-expr bool-expr ? true-expr : false-expr case target-expr when comparison [, comparison]... [then] body when comparison [, comparison]... [then] body ... [else body] end (comparisons may be regexen) loop do body end while bool-expr [do] body end until bool-expr [do] body end begin body end while bool-expr begin body end until bool-expr for name[, name]... in expr [do] body end expr.each do | name[, name]... | body end expr while bool-expr expr until bool-expr break terminates loop immediately. redo immediately repeats w/o rerunning the condition. next starts the next iteration through the loop. retry restarts the loop, rerunning the condition. Invoking a Method Nearly everything available in a method invocation is optional, consequently the syntax is very difficult to follow. Here are some examples: method obj.method Class::method method(key1 => val1, key2 => val2) is one argument for def method(hash_arg) ! method(arg1, *[arg2, arg3]) becomes: method(arg1, arg2, arg3) as ugly as you want it to be: method(arg1, key1 => val1, key2 => val2, *splat_arg) #{ block } invocation := [receiver ('::' | '.')] name [ parameters ] [ block ] parameters := ( [param]* [, hashlist] [*array] [&aProc] ) block := { blockbody } | do blockbody end Defining a Class Class names begin w/ capital character. class Identifier [< superclass ] expr.. end # singleton classes, add methods to a single instance class << obj expr.. end Defining a Module module Identifier expr.. end Defining a Method def method_name(arg_list, *list_expr, &block_expr) expr.. end # singleton method def expr.identifier(arg_list, *list_expr, &block_expr) expr.. end All items of the arg list, including parens, are optional. Arguments may have default values (name=expr). Method_name may be operators (see above). The method definitions can not be nested. Methods may override operators: |, ^, &, <=>, ==, ===, =~, >, >=, <, <=, +, -, *, /, %, **, <<, >>, ~, +@, -@, [], []= (2 args) Access Restriction public - totally accessible. protected - accessible only by instances of class and direct descendants. Even through hasA relationships. (see below) private - accessible only by instances of class (must be called nekkid no "self." or anything else). Restriction used w/o arguments set the default access control. Used with arguments, sets the access of the named methods and constants. class A protected def protected_method # nothing end end class B < A public def test_protected myA = A.new myA.protected_method end end b = B.new.test_protected Accessors Class Module provides the following utility methods: attr_reader <attribute>[, <attribute>]... Creates a read-only accessor for each <attribute>. attr_writer <attribute>[, <attribute>]... Creates a write-only accessor for each <attribute>. attr <attribute> [, <writable>] Equivalent to "attr_reader <attribute>; attr_writer <attribute> if <writable>" attr_accessor <attribute>[, <attribute>]... Equivalent to "attr <attribute>, TRUE" for each argument. Aliasing alias :new :old alias_method :new, :old Creates a new reference to whatever old referred to. old can be any existing method, operator, global. It may not be a local, instance, constant, or class variable. Blocks, Closures, and Procs Blocks/Closures blocks must follow a method invocation: invocation do ... end invocation { ... } Blocks remember their variable context, and are full closures. Blocks are invoked via yield and may be passed arguments. Brace form has higher precedence and will bind to the last parameter if invocation made w/o parens. do/end form has lower precedence and will bind to the invocation even without parens. Proc Objects Created via: Kernel#proc Proc#new By invoking a method w/ a block argument. See class Proc for more information. Exceptions, Catch, and Throw Exception NoMemoryError ScriptError LoadError NotImplementedError SyntaxError SignalException Interrupt StandardError (default for rescue) ArgumentError IOError EOFError IndexError LocalJumpError NameError NoMethodError RangeError FloatDomainError RegexpError RuntimeError (default for raise) SecurityError SystemCallError Errno::* SystemStackError ThreadError TypeError ZeroDivisionError SystemExit fatal Raising and Rescuing raise ExceptionClass[, "message"] begin expr.. [rescue [error_type [=> var],..] expr..].. [else expr..] [ensure expr..] end Catch and Throw catch (:label) do ... end throw :label jumps back to matching catch and terminates the block. + can be external to catch, but has to be reached via calling scope. + Hardly ever needed. Standard Library Ruby comes with an extensive library of classes and modules. Some are built-in, and some are part of the standard library. You can distinguish the two by the fact that the built-in classes are in fact, built-in. There are no dot-rb files for them. Built-in Library Class Hierarchy Object Hash Symbol IO File Continuation File::Stat Data NilClass Exception (see tree above) Array Proc String Numeric Float Integer Bignum Fixnum Regexp Thread Module Class ThreadGroup Method UnboundMethod Struct Struct::Tms TrueClass Time Dir Binding Range MatchData FalseClass Modules Comparable Enumerable Errno FileTest GC Kernel Marshal Math ObjectSpace Precision Process Standard Library The essentials: benchmark.rb a simple benchmarking utility cgi-lib.rb decode CGI data - simpler than cgi.rb cgi.rb CGI interaction date.rb date object (compatible) debug.rb ruby debugger delegate.rb delegate messages to other object English.rb access global variables by english names fileutils.rb file utility methods for copying, moving, removing, etc. find.rb traverse directory tree jcode.rb UTF-8 and Japanese String helpers (replaces String methods) net/*.rb Networking classes of all kinds observer.rb observer design pattern library (provides Observable) open-uri.rb good wrapper for net/http, net/https and net/ftp open3.rb open subprocess connection stdin/stdout/stderr ostruct.rb python style object (freeform assignment to instance vars) parsearg.rb argument parser using getopts pp prettier debugging output, 'p' on steroids. profile.rb ruby profiler - find that slow code! pstore.rb persistent object strage using marshal rexml/*.rb XML toolkit singleton.rb singleton design pattern library stringio lets you use an IO attached to a string. tempfile.rb temporary file that automatically removed test/unit unit testing framework time.rb extension to Time class with a lot of converters tracer.rb execution tracer webrick Fairly spiffy web server yaml alternative readable serialization format Tools ruby Command Line Options -0[octal] specify record separator (\0, if no argument). -a autosplit mode with -n or -p (splits $_ into $F). -c check syntax only. -Cdirectory cd to directory, before executing your script. --copyright print the copyright and exit. -d set debugging flags (set $DEBUG to true). -e 'command' one line of script. Several -e's allowed. -F regexp split() pattern for autosplit (-a). -h prints summary of the options. -i[extension] edit ARGV files in place (make backup if extension supplied). -Idirectory specify $LOAD_PATH directory (may be used more than once). -Kkcode specifies KANJI (Japanese) code-set. -l enable line ending processing. -n assume 'while gets(); ... end' loop around your script. -p assume loop like -n but print line also like sed. -rlibrary require the library, before executing your script. -s enable some switch parsing for switches after script name. -S look for the script using PATH environment variable. -T[level] turn on tainting checks. -v print version number, then turn on verbose mode. --version print the version and exit. -w turn warnings on for your script. -x[directory] strip off text before #! line and perhaps cd to directory. -X directory causes Ruby to switch to the directory. -y turns on compiler debug mode. Environment Variables DLN_LIBRARY_PATH Search path for dynamically loaded modules. RUBYLIB Additional search paths. RUBYLIB_PREFIX Add this prefix to each item in RUBYLIB. Windows only. RUBYOPT Additional command line options. RUBYPATH With -S, searches PATH, or this value for ruby programs. RUBYSHELL Shell to use when spawning. irb irb [options] [script [args]] The essential options are: -d Sets $DEBUG to true. Same as "ruby -d ..." -f Prevents the loading of ~/.irb.rc. -h Get a full list of options. -m Math mode. Overrides --inspect. Loads "mathn.rb". -r module Loads a module. Same as "ruby -r module ..." -v Prints the version and exits. --inf-ruby-mode Turns on emacs support and turns off readline. --inspect Turns on inspect mode. Default. --noinspect Turns off inspect mode. --noprompt Turns off the prompt. --noreadline Turns off readline support. --prompt Sets to one of 'default', 'xmp', 'simple', or 'inf-ruby'. --readline Turns on readline support. Default. --tracer Turns on trace mode. Besides arbitrary ruby commands, the special commands are: exit exits the current session, or the program fork block forks and runs the given block cb args changes to a secified binding source file loads a ruby file into the session irb [obj] starts a new session, with obj as self, if specified conf[.key[= val]] access the configuration of the session jobs lists the known sessions fg session switches to the specifed session kill session kills a specified session Session may be specified via session#, thread-id, obj, or self. xmp require "irb/xmp" xmp "something to eval" # or: x = XMP.new x.puts "something to eval" ruby-mode TODO: I don't have a freakin clue how to use the inferior ruby thing... I always fire up a shell in emacs... DOH! Debugger To invoke the debugger: ruby -r debug ... To use the debugger: b[reak] [file:|class:]<line|method b[reak] [class.]<line|method set breakpoint to some position wat[ch] expression set watchpoint to some expression cat[ch] exception set catchpoint to an exception b[reak] list breakpoints cat[ch] show catchpoint del[ete][ nnn] delete some or all breakpoints disp[lay] expression add expression into display expression list undisp[lay][ nnn] delete one particular or all display expressions c[ont] run until program ends or hit breakpoint s[tep][ nnn] step (into methods) one line or till line nnn n[ext][ nnn] go over one line or till line nnn w[here] display frames f[rame] alias for where l[ist][ (-|nn-mm)] list program, - lists backwards nn-mm lists given lines up[ nn] move to higher frame down[ nn] move to lower frame fin[ish] return to outer frame tr[ace] (on|off) set trace mode of current thread tr[ace] (on|off) all set trace mode of all threads q[uit] exit from debugger v[ar] g[lobal] show global variables v[ar] l[ocal] show local variables v[ar] i[nstance] object show instance variables of object v[ar] c[onst] object show constants of object m[ethod] i[nstance] obj show methods of object m[ethod] class|module show instance methods of class or module th[read] l[ist] list all threads th[read] c[ur[rent]] show current thread th[read] [sw[itch]] nnn switch thread context to nnn th[read] stop nnn stop thread nnn th[read] resume nnn resume thread nnn p expression evaluate expression and print its value h[elp] print this help everything else evaluate empty repeats the last command rdoc Structure = Level One Heading == Level Two Heading, and so on * bullet list - bullet list 1. numbered list [cat] labeled list cat:: labeled list, tabular format --- horizontal line (rule) Formatting _italic_ italic text *bold* bold text +typewriter+ typewriter or mono-spaced text \+escaped+ escaped, not special formatting Hyperlinks http://example.com/index.html converts to external link, shows link [home]http://example.com/index.html converts to external link, shows "home" link:/some/file/on/my/disk converts to link to local file Metadata # :yields: ... on method description, ... are yield parameters # :nodoc:[all] don't include this element in documentation, all for sub-elements too # :doc: force an element to be documented # :notnew: do not assume initialize arguments are for the new method # -- in comment stop rdoc processing # ++ in comment start rdoc processing again # :include:filename include filename at this point # :title:text set the title for this document to text # :main:name set the class, module, or file to appear on the index page =begin the everything between a line beginning with `=begin' and that with `=end' will be skipped by the ruby interpreter. =end Command Line Options Run `rdoc --help` for full listing. Here are the more common flags: --all, -a include all methods (not just public) in the output --diagram, -d Generate diagrams showing modules and classes. --exclude, -x pattern Do not process files or directories matching pattern. --force-update, -U forces to scan all sources even if newer than the flag file. --fmt, -f format name Output using output formatters: chm, html, ri, xml (pluggable) --inline-source, -S Show method source code inline, rather than via a popup link --main, -m name 'name' will be the initial page displayed --op, -o dir Set the output directory. --ri, -r generate ri output files to ~/.rdoc. --style, -s stylesheet url Specifies the URL of a separate stylesheet. --template, -T template Set the template used when generating output --title, -t text Set 'text' as the title for the output. Mindshare, Idiom and Patterns Object Design Visitor Pattern By defining the method #each and including Enumerable, you get to use all the methods in Enumerable: class Mailbox include Enumerable # ... def each @mail.each do # ... yield end end end Class SimpleDelegator, DelegateClass foo = Object.new foo2 = SimpleDelegator.new(foo) foo.hash == foo2.hash # => false Foo = DelegateClass(Array) class ExtArray<DelegateClass(Array) ... end Module Observer monitor.add_observer(self) ... def update ... notify_observers(data, ...) end Module Singleton class Klass include Singleton # ... end a, b = Klass.instance, Klass.instance a == b # => true a.new # raises NoMethodError Other Third-party Libraries Racc See i.loveruby.net /en /man /racc Test::Unit assert(boolean, message=nil) assert_block(message="assert_block failed.") do ... end assert_equal(expected, actual, message=nil) assert_in_delta(expected_float, actual_float, delta, message="") assert_instance_of(klass, object, message="") assert_kind_of(klass, object, message="") assert_match(pattern, string, message="") assert_nil(object, message="") assert_no_match(regexp, string, message="") assert_not_equal(expected, actual, message="") assert_not_nil(object, message="") assert_not_same(expected, actual, message="") assert_nothing_raised(*args) assert_nothing_thrown(message="") do ... end assert_operator(object1, operator, object2, message="") assert_raises(expected_exception_klass, message="") do ... end assert_respond_to(object, method, message="") assert_same(expected, actual, message="") assert_send(send_array, message="") assert_throws(expected_symbol, message="") do ... end flunk(message="Flunked")