From: Charles Mills <cmills@...>
Date: 2004-08-04T02:51:31+09:00
Subject: Re: __call__ equivalent?

On Aug 3, 2004, at 10:31 AM, Kevin Howe wrote:

> Does Ruby have an equivalent of Python's __call__ method?
>

Not sure what Python's __call__ does, but ...

meth.call(args, ...) => obj
  meth[args, ...] => obj


Invokes the meth with the specified arguments, returning the method�s 
return value.
    m = 12.method("+")
    m.call(3)    #=> 15
    m.call(20)   #=> 32

---------

prc.call(params,...) => obj
  prc[params,...] => obj


Invokes the block, setting the block�s parameters to the values in 
params using something close to method calling semantics. Generates a 
warning if multiple values are passed to a proc that expects just one 
(previously this silently converted the parameters to an array).

  For procs created using Kernel.proc, generates an error if the wrong 
number of parameters are passed to a proc with multiple parameters. For 
procs created using Proc.new, extra parameters are silently discarded.

  Returns the value of the last expression evaluated in the block. See 
also Proc#yield.
    a_proc = Proc.new {|a, *b| b.collect {|i| i*a }}
    a_proc.call(9, 1, 2, 3)   #=> [9, 18, 27]
    a_proc[9, 1, 2, 3]        #=> [9, 18, 27]
    a_proc = Proc.new {|a,b| a}
    a_proc.call(1,2,3)


  produces:
    prog.rb:5: wrong number of arguments (3 for 2) (ArgumentError)
     from prog.rb:4:in `call'
     from prog.rb:5