From: Paul McMahon <paul.mcmahon@...>
Date: 2008-12-04T19:01:10+09:00
Subject: [ruby-core:20304] Re: Proposal: Method#get_args

I am late to this discussion, but I am a bit concerned about the
handling of default arguments, as you seem to be returning the result
of the calculated default arguments every time you call get_args.  For
example:

def foo(bar=[]); end
method(:foo).get_args #=> [[[:bar, []]], nil, nil]

I am assuming everytime get_args gets called, a new array is created.
Now if the default argument is something like an array or string, this
isn't a problem.  However, the value for a default argument can be an
ruby statement, whose result is calculated each time the method is
invoked.  For instance, a contrived example is:

$i = 0
def foo(bar=($i +=1)); end
foo
$i #=> 1

Now, the way your get_args is working, if you call get args;

method(:foo).get_args #=> [[[:bar, 2], nil, nil]
$i #=> 2

This is probably unexpected and undesirable behaviour.

You could get around this by returning a Proc in the tuple, but
perhaps something more object oriented would be nicer in the first
place.

For example,

m = method(:foo)
m.splat_args? #=> false
m.proc? #=> false
args = m.arguments #=> [ Proc ]
args.first.call #=> 3

would be nicer to work with, for me at least.