Confusion Over Keyword Arguments

ruby-talk
1

Yes, I think this is one of the reasons we started leaning towards using
'=' instead. Maybe we should stick with '=>' - no issues with symbols
or assignment, and people are used to it.

Regards,

Dan

···

-----Original Message-----
From: list-bounce@example.com
[mailto:list-bounce@example.com] On Behalf Of E. Saynatkari
Sent: Thursday, March 02, 2006 2:22 PM
To: ruby-talk ML
Subject: Re: Confusion Over Keyword Arguments

Daniel Berger wrote:
> Yukihiro Matsumoto wrote:
>>
>>
>> foo(1, foo:3) # (a=1, b={:foo=>3}) or (a=1,b=0,c=[{:foo=>3}])?
>
> Error. There's no 'foo' parameter. Passing a literal hash would
> require {}.
>
>> foo(1, 2, 8, c:5) # c={:c=>5}) or c=[8,{:c=>5}] or error?
>
> Hm. Either an error or c = [5], depending on whether or
not your want
> to
> declare that, once a positional is used, there's no going
back after the
> fact.
>
>> args = [1, {:b=>2, foo=>5}]
>> foo(*args) # (a=1,b={:b=>2, foo=>5}) or
(a=1,b=2,c=[{:foo=>5}])?
>
> a = 1, b = {:b=>2, foo=>5}, since you've passed a literal hash.
>
> Here's the latest test case we had for Sydney. Note that Sydney
> assumes
> that
> all method arguments automatically become keyword
arguments. There's no
> syntax
> for explicitly declaring that a given method parameter is a valid
> keyword argument.
>
> For the kids following along at home, also see
>
http://redhanded.hobix.com/inspect/namedParametersArenTTheyAllNamed.ht
> ml
> for
> further discussion on the subject.
>
> Regards,
>
> Dan

Slightly off-topic but I found this part curious:

> # You can use named parameters, using the name of the parameter
defined in
> # in the method itself. It must be the name of the parameter,
followed by
> # a colon, followed by the value. Spaces between the parameter
name, colon
> # and value are not allowed.

Why is this? foo: bar would seem to be more legible with the
added benefit of no confusion with the scope operator :: nor Symbols.

Your testcases do not seem to cover the scope completely and
Symbols are not included at all. Maybe add something like

  def test_corner_cases()
    # Symbols
    assert_nothing_raised {@foo.bar x:1, y:2, z::symbol}

    # Scopes
    assert_nothing_raised {@foo.bar A::B, y:2, z:3}
    assert_nothing_raised {@foo.bar x:1, y:2, z:::Object}

   assert_nothing_raised{ @foo.bar(z:1, x:2, y:3) }
  end # test_corner_cases

To cover those.

2

Berger, Daniel wrote:

>>
> to
> Here's the latest test case we had for Sydney. Note that Sydney
http://redhanded.hobix.com/inspect/namedParametersArenTTheyAllNamed.ht
> # You can use named parameters, using the name of the parameter
Your testcases do not seem to cover the scope completely and
   assert_nothing_raised{ @foo.bar(z:1, x:2, y:3) }
  end # test_corner_cases

To cover those.

Yes, I think this is one of the reasons we started leaning towards using
'=' instead. Maybe we should stick with '=>' - no issues with symbols
or assignment, and people are used to it.

Both problems should be fixed by mandating that there
be a space between foo: and its argument :slight_smile: What other
parsing issues that might bring is different.

Regards,

Dan

E

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