class Proc
Public Class Methods
Wrap the argument in a proc. Simply returns the argument if it is already a Proc
object.
TODO: Would this make more sense as ‘Kernel#Proc()` method,
akin to `Integer()` and the like?
Returns [Proc]
Credit: Sean Mackesey
# File lib/core/facets/proc/wrap.rb, line 13 def self.wrap(arg) Proc === arg ? arg : Proc.new{ arg } end
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
# File lib/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.
# File lib/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 by 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'
# File lib/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
# File lib/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
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
# File lib/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
# File lib/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