--- name: "jirb" section: "1" platform: "linux" package: "jruby" version: "9.4.8.0+ds-3" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/jirb" --- # jirb(1) interactive JRuby ## NAME jirb1.3 - interactive JRuby ## SYNOPSIS **jirb** \[*options*\] ## DESCRIPTION irb stands for \`interactive JRuby'. irb is a tool to execute interactively JRuby expressions read from stdin. Use of jirb is easy if you know JRuby. Executing jirb, prompts are displayed as follows. Then, enter expression of ruby. Input is executed when it is syntacticaly completed. ``` $ jirb1.3 irb(main):001:0> 1+2 3 irb(main):002:0> class Foo irb(main):003:1> def foo irb(main):004:2> print 1 irb(main):005:2> end irb(main):006:1> end nil irb(main):007:0> ``` And, Readline extension module can be used with irb. Using Readline is the standard default action if Readline is installed. ## OPTIONS - **-f** suppress read ~/.irbrc - **-m** bc mode (fraction or matrix are available) - **-d** set $DEBUG to true (same as \`ruby -d') - **-r load-module** same as \`ruby -r' - **--inspect** uses \`inspect' for output (the default except bc mode) - **--noinspect** doesn't uses inspect for output - **--readline** uses Readline extension module - **--noreadline** doesn't use Readline extension module - **--prompt prompt-mode** - **--prompt-mode prompt-mode** switches prompt mode. Pre-defined prompt modes are \`default', \`simple', \`xmp' and \`inf-ruby' - **--inf-ruby-mode** uses prompt appreciate for inf-ruby-mode on emacs. Suppresses --readline. - **--simple-prompt** simple prompt mode - **--noprompt** no prompt - **--tracer** display trace for each execution of commands. - **--back-trace-limit n** displays backtrace top n and tail n. The default value is 16. - **--irb\_debug n** sets internal debug level to n (It shouldn't be used) - **-v, --version** prints the version of irb ## CONFIGURATIONS jirb reads \`~/.irbrc' when it is invoked. If \`~/.irbrc' doesn't exist jirb try to read in the order \`.irbrc', \`irb.rc', \`\_irbrc' then \`$irbrc'. The following is alternative to the command line option. To use them type as follows in a jirb session. ``` IRB.conf[:IRB_NAME]="irb" IRB.conf[:MATH_MODE]=false IRB.conf[:USE_TRACER]=false IRB.conf[:USE_LOADER]=false IRB.conf[:IGNORE_SIGINT]=true IRB.conf[:IGNORE_EOF]=false IRB.conf[:INSPECT_MODE]=nil IRB.conf[:IRB_RC] = nil IRB.conf[:BACK_TRACE_LIMIT]=16 IRB.conf[:USE_LOADER] = false IRB.conf[:USE_READLINE] = nil IRB.conf[:USE_TRACER] = false IRB.conf[:IGNORE_SIGINT] = true IRB.conf[:IGNORE_EOF] = false IRB.conf[:PROMPT_MODE] = :DEFALUT IRB.conf[:PROMPT] = {...} IRB.conf[:DEBUG_LEVEL]=0 IRB.conf[:VERBOSE]=true ``` ## Customizing prompt To customize the prompt you set a variable ``` IRB.conf[:PROMPT] ``` For example, describe as follows in \`.irbrc'. ``` IRB.conf[:PROMPT][:MY_PROMPT] = { # name of prompt mode :PROMPT_I => nil, # normal prompt :PROMPT_S => nil, # prompt for continuated strings :PROMPT_C => nil, # prompt for continuated statement :RETURN => " ==>%s\n" # format to return value } ``` Then, invoke irb with the above prompt mode by ``` $ jirb1.3 --prompt my-prompt ``` Or add the following in \`.irbrc'. ``` IRB.conf[:PROMPT_MODE] = :MY_PROMPT ``` Constants PROMPT\_I, PROMPT\_S and PROMPT\_C specifies the format. In the prompt specification, some special strings are available. ``` %N command name which is running %m to_s of main object (self) %M inspect of main object (self) %l type of string(", ', /, ]), `]' is inner %w[...] %NNi indent level. NN is degits and means as same as printf("%NNd"). It can be omitted %NNn line number. %% % ``` For instance, the default prompt mode is defined as follows: IRB.conf\[:PROMPT\_MODE\]\[:DEFAULT\] = { - **PROMPT\_I =\> "%N(%m):%03n:%i\> ",** - **PROMPT\_S =\> "%N(%m):%03n:%i%l ",** - **PROMPT\_C =\> "%N(%m):%03n:%i\* ",** - **RETURN =\> "%s\\n"}** RETURN is used to printf. ## Configuring subirb The command line option or IRB.conf specify the default behavior of (sub)irb. On the other hand, each conf of in the next sction \`6. Command' is used to individually configure (sub)irb. If proc is set to IRB.conf\[:IRB\_RC\], its subirb will be invoked after execution of that proc under giving the context of irb as its argument. By this mechanism each subirb can be configured. ## Command For irb commands, both simple name and \`irb\_'-prefixed name are prepared. - **exit, quit, irb\_exit** Quits (sub)irb. if you've done cb (see below), exit from the binding mode. - **conf, irb\_context** Displays current configuration. Modifying the configuration is achieved by sending message to \`conf'. - **conf.back\_trace\_limit** Sets display lines of backtrace as top n and tail n. The default value is 16. - **conf.debug\_level = N** Sets debug level of irb. - **conf.ignore\_eof = true/false** Whether ^D (control-d) will be ignored or not. If false is set, ^D means quit. - **conf.ignore\_sigint= true/false** Whether ^C (control-c) will be ignored or not. If false is set, ^D means quit. If true, ``` during input: cancel inputing then return to top level. during execute: abondon current execution. ``` - **conf.inf\_ruby\_mode = true/false** Whether inf-ruby-mode or not. The default value is false. - **conf.inspect\_mode = true/false/nil** Specifies inspect mode. true: display inspect false: display to\_s nil: inspect mode in non math mode, ``` non inspect mode in math mode. ``` - **conf.irb\_level** The level of cb. - **conf.math\_mode** Whether bc mode or not. - **conf.use\_loader = true/false** Whether irb's own file reader method is used when load/require or not. This mode is globaly affected (irb wide). - **conf.prompt\_c** prompt for a continuating statement (e.g, immediately after of \`if') - **conf.prompt\_i** standard prompt - **conf.prompt\_s** prompt for a continuating string - **conf.rc** Whether ~/.irbrc is read or not. - **conf.use\_prompt = true/false** Prompting or not. - **conf.use\_readline = true/false/nil** Whether readline is used or not. true: uses false: doesn't use nil: intends to use readline except for inf-reuby-mode (default) - **conf.verbose=T/F** Whether verbose messages are display or not. - **cb, irb\_change\_binding \[obj\]** Enter new binding which has a distinct scope of local variables. If obj is given, obj will be self. - **irb \[obj\]** Invoke subirb. If obj is given, obj will be self. - **jobs, irb\_jobs** List of subirb - **fg n, irb\_fg n** Switch into specified subirb. The following is candidates of n: ``` irb number thhread irb object self(obj which is specified of irb obj) ``` - **kill n, irb\_kill n** Kill subirb. The means of n is as same as the case of irb\_fg. ## System variable - **\_** The latest value of evaluation (it is local) ## Session Example ``` $ jirb1.3 irb(main):001:0> irb # invoke subirb irb#1(main):001:0> jobs # list of subirbs #0->irb on main (# : stop) #1->irb#1 on main (# : running) nil irb#1(main):002:0> fg 0 # switch job nil irb(main):002:0> class Foo;end nil irb(main):003:0> irb Foo # invoke subirb which has the ``` ``` # context of Foo ``` ``` irb#2(Foo):001:0> def foo # define Foo#foo irb#2(Foo):002:1> print 1 irb#2(Foo):003:1> end nil irb#2(Foo):004:0> fg 0 # switch job nil irb(main):004:0> jobs # list of job #0->irb on main (# : running) #1->irb#1 on main (# : stop) #2->irb#2 on Foo (# : stop) nil irb(main):005:0> Foo.instance_methods # Foo#foo is defined asurely ["foo"] irb(main):006:0> fg 2 # switch job nil irb#2(Foo):005:0> def bar # define Foo#bar irb#2(Foo):006:1> print "bar" irb#2(Foo):007:1> end nil irb#2(Foo):010:0> Foo.instance_methods ["bar", "foo"] irb#2(Foo):011:0> fg 0 nil irb(main):007:0> f = Foo.new # irb(main):008:0> irb f # invoke subirb which has the ``` ``` # context of f (instance of Foo) ``` ``` irb#3(#):001:0> jobs #0->irb on main (# : stop) #1->irb#1 on main (# : stop) #2->irb#2 on Foo (# : stop) #3->irb#3 on # (# : running) nil irb#3(#):002:0> foo # evaluate f.foo 1nil irb#3(#):003:0> bar # evaluate f.bar barnil irb#3(#):004:0> kill 1, 2, 3# kill job nil irb(main):009:0> jobs #0->irb on main (# : running) nil irb(main):010:0> exit # exit ``` ## Restrictions Because irb evaluates the inputs immediately after the input is syntactically completed, irb gives slight different results than directly using ruby. Known differences are pointed out here. ## Declaration of the local variable The following causes an error in ruby: ``` eval "foo = 0" foo -- -:2: undefined local variable or method `foo' for # (NameError) --- NameError ``` Though, the above will successfully done by irb. ``` >> eval "foo = 0" ``` ``` => 0 >> foo => 0 ``` Ruby evaluates a code after reading entire of code and determination of the scope of local variables. On the other hand, irb do immediately. More precisely, irb evaluate at first ``` evel "foo = 0" ``` then foo is defined on this timing. It is because of this incompatibility. If you'd like to detect those differences, begin...end can be used: ``` >> begin ?> eval "foo = 0" >> foo >> end NameError: undefined local variable or method `foo' for # (irb):3 (irb_local_binding):1:in `eval' ``` ## Here-document Implementation of Here-document is incomplete. ## Symbol Irb can not always recognize a symbol as to be Symbol. Concretely, an expression have completed, however Irb regard it as continuation line.