How I Want Ruby's `Object#method` To Work

rant.md

How I Want Ruby's Object#method To Work

The simple case, is this guy:

> m = SecureRandom.method(:hex)
=> #<Method: SecureRandom.hex>
> m.call
=> "5928aab178404945fb560a249b67a000"
> m.call
=> "d5ba69ac2e9dc8632aee7bf3212f6d67"

But, what I want, is a fully curried function. Something like this:

> m = SecureRandom.method(:hex, 6)
=> #<Method: SecureRandom.hex>
> m.call
=> "bd131d38de3c"
> m.call
=> "4e5a20936be0"

But Object#method doesn't take more than one argument. So, to get the effect I want, I have to do something like this:

> m = -> { SecureRandom.hex(6) }
=> #<Proc:0x000000034144b8@(pry):7 (lambda)>
> m.call
=> "bd131d38de3c"
> m.call
=> "4e5a20936be0"

It's not a huge thing, just a little sugar, but still.

class Object
  alias_method :original_method, :method
  def method(*args)
    Proc.new do |*pargs|
      all_args = args[1..-1] + pargs
      original_method(args[0]).call(*all_args)
    end
  end
end

I wouldn't actually use it in production, nor do I know if the closures are actually properly preserved.

Normal usage:

>> m1 = SecureRandom.method(:hex)
=> #<Proc:[email protected]:5>
>> m1.call
=> "5532eba830603b73958479d42f42f7ce"
>> m1.call(10)
=> "601660c3bfaf317ef43a"

Turbo button usage:

>> m2 = SecureRandom.method(:hex, 10)
=> #<Proc:[email protected]:5>
>> m2.call
=> "6fdee86fbcc3d2ecde5b"

Extra args FTL:

>> m2.call(12)
ArgumentError: wrong number of arguments (2 for 1)
    from test.rb:7:in `hex'
    from test.rb:7:in `call'
    from test.rb:7:in `method'
    from test.rb:17:in `call'
    from test.rb:17
    from :0

So @avdi pointed out Proc#curry. And I tried it out, but it's a bit weird about arity:

> p = SecureRandom.method(:hex).to_proc
=> #<Proc:0x000000030b2590 (lambda)>
> p.airty
=> -1
> p1 = p.curry
=> #<Proc:0x0000000312f400 (lambda)>
> p1.arity
=> -1
> p1.call
=> "de22fd26a6f63516f9a1c32147cadc44"
> p1.call(5)
=> "1f5e2b31f6"
> p2 = p.curry[5]
=> "ed76826b41"
> # Oh. That's not a Proc...
> p2.call
NoMethodError: undefined method 'call' for "ed76826b41":String
> p3 = p.curry(1)[5]
=> "6c08b6f144"
> # That's not one, either...
> p4 = p.curry(2)[5]
=> #<Proc:0x000000031e4fd0 (lambda)>
> # OK. Closerrrrrr...
> p4.call
=> #<Proc:0x000000031f8cd8 (lambda)>
> # Uh... no.
> p4.call(0)
ArgumentError: wrong number of arguments (2 for 1)
from /home/ben/.rbenv/versions/1.9.3-p286/lib/ruby/1.9.1/securerandom.rb:139:in 'hex'
> # Shit.

Basically, as soon as the arity of the curried function is met, it evaluates it down, so you can't fill the args all up and then wait to call it... without explicitly making a lambda.

Name my method Object#cmethod and call it a day :)