support callable prepare objects in Schema::Argument (fixes #1786)

[modosc]

No description provided.

[rmosolgo]

Thanks for the fix here! I'm going to change it on master to use is_a?/respond_to?, for performance:

# bench.rb
require "benchmark/ips"

def with_proc(callable)
  case callable
  when String, Symbol
    callable
  when ->(x) { x.respond_to?(:call) }
    callable
  else
    nil
  end
end

def with_respond_to(callable)
  if callable.is_a?(String) || callable.is_a?(Symbol)
    callable
  elsif callable.respond_to?(:call)
    callable
  else
    nil
  end
end

callable_input = ->(x) { x }

Benchmark.ips do |x|
  x.report("proc condition") { with_proc(callable_input) }
  x.report("respond_to?/is_a?") { with_respond_to(callable_input) }
  x.compare!
end

$ ruby bench.rb
Warming up --------------------------------------
      proc condition    85.632k i/100ms
   respond_to?/is_a?   210.167k i/100ms
Calculating -------------------------------------
      proc condition      1.196M (± 3.5%) i/s -      5.994M in   5.020018s
   respond_to?/is_a?      5.023M (± 3.7%) i/s -     25.220M in   5.027962s

Comparison:
   respond_to?/is_a?:  5023030.1 i/s
      proc condition:  1195574.0 i/s - 4.20x  slower