An irb inspector

In order to create your own custom inspector there are two things you should be aware of:

Inspector uses inspect_value, or inspect_proc, for output of return values.

This also allows for an optional init+, or init_proc, which is called when the inspector is activated.

Knowing this, you can create a rudimentary inspector as follows:

irb(main):001:0> ins = IRB::Inspector.new(proc{ |v| "omg! #{v}" })
irb(main):001:0> IRB.CurrentContext.inspect_mode = ins # => omg! #<IRB::Inspector:0x007f46f7ba7d28>
irb(main):001:0> "what?" #=> omg! what?
Methods
D
I
K
N
Constants
INSPECTORS = {}
 

Default inspectors available to irb, this includes:

:pp

Using Kernel#pretty_inspect

:yaml

Using YAML.dump

:marshal

Using Marshal.dump
Class Public methods
def_inspector(key, arg=nil, &block)

Example

Inspector.def_inspector(key, init_p=nil){|v| v.inspect}
Inspector.def_inspector([key1,..], init_p=nil){|v| v.inspect}
Inspector.def_inspector(key, inspector)
Inspector.def_inspector([key1,...], inspector)

Source: show | on GitHub 

# File lib/irb/inspector.rb, line 63
  def self.def_inspector(key, arg=nil, &block)
#     if !block_given?
#       case arg
#       when nil, Proc
#     inspector = IRB::Inspector(init_p)
#       when Inspector
#     inspector = init_p
#       else
#     IRB.Raise IllegalParameter, init_p
#       end
#       init_p = nil
#     else
#       inspector = IRB::Inspector(block, init_p)
#     end

    if block_given?
      inspector = IRB::Inspector(block, arg)
    else
      inspector = arg
    end

    case key
    when Array
      for k in key
        def_inspector(k, inspector)
      end
    when Symbol
      INSPECTORS[key] = inspector
      INSPECTORS[key.to_s] = inspector
    when String
      INSPECTORS[key] = inspector
      INSPECTORS[key.intern] = inspector
    else
      INSPECTORS[key] = inspector
    end
  end
keys_with_inspector(inspector)

Determines the inspector to use where inspector is one of the keys passed during inspector definition.

Source: show | on GitHub 

# File lib/irb/inspector.rb, line 53
def self.keys_with_inspector(inspector)
  INSPECTORS.select{|k,v| v == inspector}.collect{|k, v| k}
end
new(inspect_proc, init_proc = nil)

Creates a new inspector object, using the given inspect_proc when output return values in irb.

Source: show | on GitHub 

# File lib/irb/inspector.rb, line 102
def initialize(inspect_proc, init_proc = nil)
  @init = init_proc
  @inspect = inspect_proc
end
Instance Public methods
init()

Proc to call when the inspector is activated, good for requiring dependant libraries.

Source: show | on GitHub 

# File lib/irb/inspector.rb, line 109
def init
  @init.call if @init
end
inspect_value(v)

Proc to call when the input is evaluated and output in irb.

Source: show | on GitHub 

# File lib/irb/inspector.rb, line 114
def inspect_value(v)
  @inspect.call(v)
end