From: Logan Capaldo <logancapaldo@...>
Date: 2006-03-02T05:47:04+09:00
Subject: Re: Confusion Over Keyword Arguments


On Mar 1, 2006, at 3:32 PM, Mr. Big wrote:

> Ruby 2.0 will include new syntax for hash literals: {a:3, b:4}.  
> However,
> one can leave off the {}s to create a hash. Current software uses this
> for "faked" keyword arguments.
>
> def my_meth(options={})
> end
>
> (1) my_meth(:keyword => 3) # Ruby 1.8
> (2) my_meth(keyword:3, another_option:10) # Ruby 2.0
>
> Won't this create confusion? Why must keyword arguments use the same
> syntax as new hash literals? How about "=" for keyword arguments  
> instead
> (such as in python)?
>
> -- 
> Posted via http://www.ruby-forum.com/.
>


Ruby doesn't have keyword arguments at all. When you call a method  
with "keyword arguments" you are really just passing in a single  
hash. There's no confusion because the syntaxes do the exact same thing
example_hash = { a: 1, b: 2 }
my_meth(example_hash) #pass a hash as the single argument to my_meth
my_meth(a: 1, b: 2) # pass a hash as the single argument to my_meth

Neither of these will actually set local variables, the signature for  
a method like this is as follows:

def my_meth(argument_hash)
   ...
end

e.g.:

def my_meth(arg_hash)
      arg_hash[:a] + arg_hash[:b]
end

So one would say my_meth(:a => 1, :b => 2) and get back 3
or one would say my_meth(a: 1, b: 2) and get back 3
or one would say
example_hash = { :a => 1, :b => 2 }
my_meth(example_hash) # returns 3 also