.\" DO NOT MODIFY THIS FILE! it was generated by rd2

.TH irb-beta 1 "May 2001"

.SH What is irb?

.PP

irb stands for `interactive ruby'. irb is a tool to execute interactively

ruby expressions read from stdin. 

.SH Invoking

.PP

.nf

\&    % ruby \-r irb \-e0

\&    % irb

.fi

Either of the aboves. In the former style, options can be specified

as follows:

.nf

\&    % ruby \-r irb \-e0 \-\- \-v

.fi

.SH Usage

.PP

Use of irb is easy if you know ruby.  Executing irb, prompts are 

displayed as follows. Then, enter expression of ruby. A input is

executed when it is syntacticaly completed. 

.nf

\&    dim% irb

\&    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> 

.fi

And, Readline extesion module can be used with irb. Using Readline

is the standard default action if Readline is installed. 

.SH Command line option

.PP

.nf

\&    irb.rb [options] file_name opts

\&    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

.fi

.nf

\&    switches prompt mode. Pre\-defined prompt modes are

\&    `defalut', `simple', `xmp' and `inf\-ruby'

.fi

.nf

\&    \-\-inf\-ruby\-mode   uses prompt appreciate for inf\-ruby\-mode on emacs. 

.fi

.nf

\&    Suppresses \-\-readline. 

.fi

.nf

\&    \-\-simple\-prompt   simple prompt mode

\&    \-\-noprompt	    no prompt

\&    \-\-tracer	    display trace for each execution of commands.

\&    \-\-back\-trace\-limit n

.fi

.nf

\&    displayes backtrace top n and tail n. The default

\&    value is 16. 

.fi

.nf

\&    \-\-irb_debug n	    sets internal debug level to n (It shouldn't be used)

\&    \-v, \-\-version	    prints the version of irb

.fi

.SH Configurations

.PP

irb reads `~/.irbrc' when it is invoked. If `~/.irbrb' doesn't exist

irb try to read in the order `.irbrc', `irb.rc', `_irbrc' then `$irbrc'. 

The following is altanative to the command line option. To use them

type as follows in an irb session. 

.nf

\&    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

.fi

.SH Customizing prompt

.PP

To costomize the prompt you set a variable

.nf

\&    IRB.conf[:PROMPT]

.fi

For example, describe as follows in `.irbrc'. 

.nf

\&    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

\&    }

.fi

Then, invoke irb with the above prompt mode by

.nf

\&    % irb \-\-prompt my\-prompt

.fi

Or add the following in `.irbrc'. 

.nf

\&    IRB.conf[:PROMPT_MODE] = :MY_PROMPT

.fi

Constants PROMPT_I, PROMPT_S and PROMPT_C specifies the format. 

In the prompt specification, some special strings are available. 

.nf

\&    %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 ommited

\&    %NNn	line number. 

\&    %%    %

.fi

For instance, the default prompt mode is defined as follows:

IRB.conf[:PROMPT_MODE][:DEFAULT] = {

.TP

.fi

.B

PROMPT_I => "%N(%m):%03n:%i> ",

.TP

.fi

.B

PROMPT_S => "%N(%m):%03n:%i%l ",

.TP

.fi

.B

PROMPT_C => "%N(%m):%03n:%i* ",

.TP

.fi

.B

RETURN => "%s\\n"

} 

RETURN is used to printf. 

.SH Configurating subirb

.PP

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 configurate (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

aregument. By this mechanism each subirb can be configurated. 

.SH Command

.PP

For irb commands, both simple name and `irb_'\-prefixed name are prepared. 

.TP

.fi

.B

exit, quit, irb_exit

Quits (sub)irb. 

if you've done cb (see below), exit from the binding mode.

.TP

.fi

.B

conf, irb_context

Displays current configuration. Modifing the configuration is

achieved by sending message to `conf'. 

.TP

.fi

.B

conf.back_trace_limit

Sets display lines of backtrace as top n and tail n. 

The default value is 16.

.TP

.fi

.B

conf.debug_level = N

Sets debug level of irb. 

.TP

.fi

.B

conf.ignore_eof = true/false

Whether ^D (control\-d) will be ignored or not. 

If false is set, ^D means quit. 

.TP

.fi

.B

conf.ignore_sigint= true/false

Whether ^C (control\-c) will be ignored or not. 

If false is set, ^D means quit.  If true, 

.nf

\&    during input:   cancel inputing then return to top level. 

\&    during execute: abondon current execution. 

.fi

.TP

.fi

.B

conf.inf_ruby_mode = true/false

Whether inf\-ruby\-mode or not. The default value is false.

.TP

.fi

.B

conf.inspect_mode = true/false/nil

Specifies inspect mode. 

true:  display inspect

false: display to_s

nil:   inspect mode in non math mode, 

.nf

\&    non inspect mode in math mode. 

.fi

.TP

.fi

.B

conf.irb_level

The level of cb. 

.TP

.fi

.B

conf.math_mode

Whether bc mode or not. 

.TP

.fi

.B

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). 

.TP

.fi

.B

conf.prompt_c

prompt for a continuating statement (e.g, immediately after of `if')

.TP

.fi

.B

conf.prompt_i

standard prompt

.TP

.fi

.B

conf.prompt_s

prompt for a continuating string

.TP

.fi

.B

conf.rc

Whether ~/.irbrc is read or not. 

.TP

.fi

.B

conf.use_prompt = true/false

Prompting or not. 

.TP

.fi

.B

conf.use_readline = true/false/nil

Whether readline is used or not. 

true: uses 

false: doen't use

nil: intends to use readline except for inf\-reuby\-mode (default)

.TP

.fi

.B

conf.verbose=T/F

Whether verbose messages are display or not. 

.TP

.fi

.B

cb, irb_change_binding [obj]

Enter new binding which has a distinct scope of local variables. 

If obj is given, obj will be self. 

.TP

.fi

.B

irb [obj]

Invoke subirb. If obj is given, obj will be self. 

.TP

.fi

.B

jobs, irb_jobs

List of subirb

.TP

.fi

.B

fg n, irb_fg n

Switch into specified subirb. The following is candidates of n:

.nf

\&    irb number

\&    thhread

\&    irb object

\&    self(obj which is specified of irb obj)

.fi

.TP

.fi

.B

kill n, irb_kill n

Kill subirb. The means of n is as same as the case of irb_fg. 

.SH System variable

.PP

.nf

\&    _  The latest value of evaluation (it is local)

.fi

.SH Session Example

.PP

.nf

\&    dim% ruby irb.rb

\&    irb(main):001:0> irb                        # invoke subirb

\&    irb#1(main):001:0> jobs                     # list of subirbs

\&    #0\->irb on main (#<Thread:0x400fb7e4> : stop)

\&    #1\->irb#1 on main (#<Thread:0x40125d64> : 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 

.fi

.nf

\&    #              context of Foo

.fi

.nf

\&    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 (#<Thread:0x400fb7e4> : running)

\&    #1\->irb#1 on main (#<Thread:0x40125d64> : stop)

\&    #2\->irb#2 on Foo (#<Thread:0x4011d54c> : 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

\&    #<Foo:0x4010af3c>

\&    irb(main):008:0> irb f                      # invoke subirb which has the

.fi

.nf

\&    #  context of f (instance of Foo)

.fi

.nf

\&    irb#3(#<Foo:0x4010af3c>):001:0> jobs

\&    #0\->irb on main (#<Thread:0x400fb7e4> : stop)

\&    #1\->irb#1 on main (#<Thread:0x40125d64> : stop)

\&    #2\->irb#2 on Foo (#<Thread:0x4011d54c> : stop)

\&    #3\->irb#3 on #<Foo:0x4010af3c> (#<Thread:0x4010a1e0> : running)

\&    nil

\&    irb#3(#<Foo:0x4010af3c>):002:0> foo         # evaluate f.foo

\&    1nil

\&    irb#3(#<Foo:0x4010af3c>):003:0> bar         # evaluate f.bar

\&    barnil

\&    irb#3(#<Foo:0x4010af3c>):004:0> kill 1, 2, 3# kill job

\&    nil

\&    irb(main):009:0> jobs

\&    #0\->irb on main (#<Thread:0x400fb7e4> : running)

\&    nil

\&    irb(main):010:0> exit                       # exit

\&    dim% 

.fi

.SH Restrictions

.PP

Because irb evaluates the inputs immediately after the imput is

syntactically completed, irb gives slight different result than

directly use ruby. Known difference is pointed out here. 

.SH Declaration of the local variable

.PP

The following causes an error in ruby:

.nf

\&    eval "foo = 0"

\&    foo

\&    \-\-

\&    \-:2: undefined local variable or method `foo' for #<Object:0x40283118> (NameError)

\&    \-\-\-

\&    NameError

.fi

Though, the above will successfully done by irb. 

.nf

\&    >> eval "foo = 0"

.fi

.nf

\&    => 0

\&    >> foo

\&    => 0

.fi

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

.nf

\&    evel "foo = 0" 

.fi

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:

.nf

\&    >> begin

\&    ?>   eval "foo = 0"

\&    >>   foo

\&    >> end

\&    NameError: undefined local variable or method `foo' for #<Object:0x4013d0f0>

\&    (irb):3

\&    (irb_local_binding):1:in `eval'

.fi

.SH Here\-document

.PP

Implementation of Here\-document is incomplete. 

.SH Symbol

.PP

Irb can not always recognize a symbol as to be Symbol. Concretely, an

expression have completed, however Irb regard it as continuation line.