Class Proc
In: lib/facets/core/facets/proc/update.rb
lib/facets/core/facets/proc/bind_to.rb
lib/facets/core/facets/proc/partial.rb
lib/facets/core/facets/proc/compose.rb
lib/facets/core/facets/proc/curry.rb
lib/facets/core/facets/proc/to_method.rb
lib/facets/core/facets/proc/bind.rb
Parent: Object

Methods

*   bind   bind_to   compose   curry   partial   to_method  

External Aliases

call -> update
  Use a Proc as an observable.

CREDIT: Tim Pease

Public Instance methods

Operator for Proc#compose and Integer#times_collect/of.

  a = lambda { |x| x + 4 }
  b = lambda { |y| y / 2 }

  (a * b).call(4)  #=> 6
  (b * a).call(4)  #=> 4

CREDIT: Dave

[Source]

# File lib/facets/core/facets/proc/compose.rb, line 29
  def *(x)
    if Integer===x
      # collect times
      c = []
      x.times{|i| c << call(i)}
      c
    else
      # compose procs
      lambda{|*a| self[x[*a]]}
    end
  end

Bind a Proc to an object returning a Method.

NOTE: This version comes from Rails. The old Facets version used thread.rb, but I no longer think the implementaiton is thread critical. Please make a bug report if this proves wrong.

[Source]

# File lib/facets/core/facets/proc/bind.rb, line 12
  def bind(object)
    block, time = self, Time.now
    method_name = "__bind_#{time.to_i}_#{time.usec}"
    object.singleton_class.class_eval do
      define_method(method_name, &block)
      method = instance_method(method_name)
      remove_method(method_name)
      method
    end.bind(object)
  end

Bind a procedure to an object. This works wrapping instance_eval on the Proc object and then wrapping this in a new Proc.

   a = [1,2,3]
   p1 = Proc.new{ join(' ') }
   p2 = p1.bind_to(a)
   p2.call  #=> '1 2 3'

[Source]

# File lib/facets/core/facets/proc/bind_to.rb, line 12
  def bind_to(object)
    Proc.new{object.instance_eval(&self)}
  end

Returns a new proc that is the functional composition of two procs, in order.

  a = lambda { |x| x + 4 }
  b = lambda { |y| y / 2 }

  a.compose(b).call(4)  #=> 6
  b.compose(a).call(4)  #=> 4

CREDIT: Dave

[Source]

# File lib/facets/core/facets/proc/compose.rb, line 14
  def compose(g)
    raise ArgumentError, "arity count mismatch" unless arity == g.arity
    lambda{ |*a| self[ *g[*a] ] }
  end

Curry Proc object into new Proc object.

TODO: Utilize Ruby 1.9‘s curry method.

[Source]

# File lib/facets/core/facets/proc/curry.rb, line 7
  def curry(*args)
    if args.empty?
      idx = (0...arity).to_a
    else
      raise ArgumentError, "argument count is greater than prok.arity (#{args.size} > #{arity})" if args.size > arity
      raise ArgumentError, "arguments must be unique indexes" if args.uniq != args
      raise ArgumentError, "arguments must be indexes" if args.any?{ |a| !Fixnum===a }
      idx = (0...arity).to_a
      idx = args + (idx - args)
    end

    pro = self
    rec = ''
    idx.each do |i|
      rec << "proc { |a#{i}| "
    end
    rec << "pro["
    rec << (0...arity).to_a.collect{|i| "a#{i}"}.join(',')
    rec << "]"
    rec << "}" * arity

    instance_eval rec
  end

Convert a Proc object into new partial Proc object.

  a = proc { |a,b,c| a+b+c }
  b = a.partial(NA,2,NA)
  b[1,3] #=> 6

Note, the __ method, which used to be used in stay of NA, has been deprecated.

This method is similar to Proc#curry.

CREDT Trans

[Source]

# File lib/facets/core/facets/proc/partial.rb, line 24
  def partial(*args)
    Proc.new do |*spice|
      result = args.collect do |a|
        NA == a ? spice.pop : a
      end
      call(*result)
    end
  end

Convert Proc to method.

  object = Object.new

  function = lambda { |x| x + 1 }

  function.to_method(object, 'foo')

  object.foo(1)  #=> 2

[Source]

# File lib/facets/core/facets/proc/to_method.rb, line 16
  def to_method(object, name=nil)
    ##object = object || eval("self", self)
    block, time = self, Time.now
    method_name = name || "__bind_#{time.to_i}_#{time.usec}"
    begin
      object.singleton_class.class_eval do
        define_method(method_name, &block)
        method = instance_method(method_name)
        remove_method(method_name) unless name
        method
      end.bind(object)
    rescue TypeError
      object.class.class_eval do
        define_method(method_name, &block)
        method = instance_method(method_name)
        remove_method(method_name) unless name
        method
      end.bind(object)
    end
  end

[Validate]