From: Trans <transfire@...>
Date: 2005-10-25T07:22:02+09:00
Subject: Re: A comparison by example of keyword argument styles


Ara.T.Howard wrote:

> i think you cannot ever have both trailing optional arguments AND keywords
> with current ruby calling conventions since it will always be impossible to
> determine whether the last hash is a value for an optional argument or the set
> of keywords.  the only way is to have a syntax that calls methods with
> keywords that are not an inlines hash, eg
>
>    foo 42, keyword : 42.0   # optional gets default value
>    foo 42, keyword => 42.0  # optional IS a hash , keyword is not given

Ah, at first I was gogin to say "STOP! You've got this all distorted.
These are parameters, not hash keys. Related but different. So why are
you using strings? It's this:

    foo 42, keyword => 40 + 2

There is no ambiguity."

But now I see you get to this To which I say: Exactly. This is how it
ought to be -- IF done this way. Matz implementation actually is NOT
like this though and has worse problems some of which you describe
above.

> when i was coding parseargs all this became apparent very quickly.  trying to
> write a parser for any proposed syntax is a good exercise that shows how nice
> a real keyword syntax might make things.

What do you mean by real?

T.